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78 Threads found on edaboard.com: Input Signal Mixer
If the internal transistors of the Gilbert cell mixer are not biased to work in saturation (and in SA612 case, they are not) is preferable to drive the mixer at the LO input using a sine wave signal. There are many switching-type mixers where is mandatory to use square LO signal, but this is (...)
The post is insonsistent regarding intended circuit function. It's also unclear how the waveform has been acquired. I think, the mixer circuit can be also described as an AM modulator because part of the output signal is a product of both input signals, but only a small part.
In additional to the comment above, Check also LO driving signal amplitude to prevent self-mixing due to limited LO-RF isolation.If this amplitude becomes very high, LO mixes with itself at the RF input then it can generate a modulation by some phse shift.
The result is that both components, RF and LO are multiplied in a mixer, and the IF input contains the result of this product. If you need a clean translation of the "high" RF signal in the "low" IF output, use the best LO oscillator you can find. Otherwise by applying a dirty LO you get a dirty IF output. Oscillator noise problems has bee (...)
At the IF output of the mixer, always will be a signal |Frf-Flo|, whatever LO-RF isolation is. If is a heterodyne mixer (RF different frequency than LO), there is not too much impact of the LO-RF isolation, on the IF signal. If is a Direct Conversion mixer (RF almost equal to LO), any LO leakage at RF (...)
Due to limited selectivity of the RF filters, RF gain can't be arbitrarily high, otherwise off-band components could cause amplifier and mixer overload. So if you plan higher RF gain, you have to check that the signal is keeping the linear range in every part of the receiver. When we said that the RF amp has input power is -110dB
i don't think that a superhet with an IF of 455kHZ will work with an input signal of 457 kHZ. If it is going to be for a fixed (457 kHZ) reception only, I would use a domestic superhet with the mixer/oscillator re-configured as an RF amp. Get an old one with IF transformers and not fixed ceramic filters (can't change the frequency of (...)
Hi ! I am making an RF Transmitter and i have a problem with power leakage for LO port to IF port and RF port. I don't know what to do and i am little confused about how can i fix this. Source(-10 or -20dBm) 10KHz --------->mixer conv.loss=8db--------->RF port and L.O=70MHz and 7dbm I put an oscilloscope to mixers input IF and i (...)
I may want to use my spectrum analyzer for the job. The noise source operates with a pulsed input only, or can i apply a constant 28V DC to produce the hot noise?
Hi biff44 again. So, after the mixer i put one filter to cut the unwanted zone. So instead the mixer and the filter you propose a single modulator. As i understand the SSM wil need also a filter to cut the unwanted L.O freq=30.1MHz. So why a SSM and not a mixer? Also the SSM that i see here 217.34.103.131/products/ModulatorsDemodulators.s
Hi, I would like to realize this circuit: But I don't understand how to calculate resistors to have 1v input.:-( Could you explain me ? Thanks, Jérôme
Yes. And as the IF center frequency usually goes down with IF2 and IF3, it is easier to make the filter because the % bandwidth gets smaller--you have steeper rejection at the bandedges. But, you do need those filters. Lets say you had a 455 KHz third IF, and were trying to receive a 915 Mhz input frequency. If you did not have a bandpass filte
in designing down converter mixer, how to determine RF input power needed? Most of designing circuit they chose -30dB. thank you
I am designing a mixer that produces a differential output based on differential inputs from an LO and RF. My question is what is a differential input/output signal? The differential outputs are generally labelled IF+ and IF-. Does this mean the signals are just inverse of the other? If this is true why cant (...)
it is written: 50 ohms, 0 VDC, DC coupled. So, is it mandatory to remove the DC signal of my output? Am I right? What does it mean with ?DC coupled?? It means, that the input is directly connected to the mixer and does not tolerate larger amounts of superimposed DC. Small (mV range) DC offsets don't harm however. The cri
Because is radiated, and perhaps lose a lot of power, might need to put an amplifier before LO input of the mixer.
A mixer is in principle a multiplier; it multiplies for instance the local-oscillator signal with an IF input signal. Then pairs of multiples are generated in frequency spectrum. We typically choose one of them, name it RF and use filters to suppress all others. Such action is named "upconversion" and can be used to (...)
Consider the quadrature mixer as shown below. The frequency domain representation of the input signal x(t), X(f) is as shown below. Assuming that f2>>f1>>fb, draw the frequency domain representation of the signal at points a, b, c, d and e. 64380 I am not asking you to do this for me. I would maybe like someone to
Hello Every one, I want to design a analog mixer with 0.18um BICMOS process. The mixer is used to be one module in the whole chip. One input signal of the mixer is a wide-band signal, for example , its bandwidth is 50MHz. The center frequency is variable between DC and 2GHz. The other (...)
Hello, I am finding trouble in simulating the ouput of a mixer. I have two input waves one of the frequency 400.001Mhz and other input of freq 400Mhz. I need to select the 1Khz signal from the mixer output, so I placed a low pass filter after the mixer, so as to obtain the 1Khz (...)
As Zorro wrote, a mixer needs its diodes to be "pumped" by a LO input power. LO power drives AC and DC current through the diodes, alternatively opening and closing them. When you inject a low-level RF signal into it, the diode non-linearity around the I/V "knee" will generate harmonic combinations of the LO and RF frequency. Some of then (...)
I assume you are feeding input at bottom device. Noise figure will be dominated by the noise figure of that device. 4 db is a good number although you will likely get worse performance with real L.O. source sideband noise.
Hello, is any one can guide me to built a costas receiver. At the input of a mixer the LO and RF signal creates an IF signal. This IF is the frequency difference of LO and RF irrespective of their position of frequency spectrum, i mean IF=LO-RF or IF=RF-LO. I need to track this IF signal at the output of (...)
Hi, so the input signal must be sampled at IF (70 MHz) and feed to the first stage up-converter witch will translate it to IF_2 (800MHz-2GHz) wich in turn will be feed to the second stage mixer/upconverter so that it will be translated to the desired 30GHz band. LO_1 = (800MHz-2GHz) - 70MHz LO_2 = 30GHz - (800MHz-2GHz)
In Gilbert mixer, People usually said large LO signal and Small RF signal. Any one give a detail example, what's the swing value of LO & RF signal.?? Thank you very much
Hi, A subharmonic mixer will use the first harmonic (in most cases) of the LO signal you input in the mixer to mix with your IF. Let take an example: We use a subharmonic mixer, we come with a 10 Ghz LO signal in and a 1 GHz IF. The mixer will internally mix the 2*10 GHz (...)
Does it matter if the local oscillator amplitude on a mixer input (about 9Vpp) is greater than than the IF on the other mixer input (about 3Vpp)? It is a diode ring modulator.
Hello all, I have a misgiving about the voltage conversion gain of mixers, That is defined as VIF/VRF, where VIF and VRF are the input and the output voltages of the (downconversion) mixer respectively. My question is- why this definition do not include VLO (the other input of the mixer)? Let me exemplify: (...)
I'm designing a receiver front-end with a double-balnaced Gilbert mixer. I found out the LO signal swing for down-converted mixer in my case is not enough. How can I improve the LO signal swing?? I've adopted a limiter between the LO and mixer switching stage input so far Replacing this (...)
Hi - I have a Gilbert Cell, mixing the signal from 7GHz directly to 0Hz. Now sweeping both phases of the LO input signals coherent, there are constellations where the mixer delivers negativ output voltage. Can the be explained? Greetings, Thomas
I am designing a low voltage(1.8V) Gilbert cell mixer, which includes(from bottom to top) tail current mos, RF input mos, LO switching mos, and resistive load. Since LO has large amplitude, there would be a large common-mode second harmonic of LO at the drain of RF input mos, which may cause the RF input mos to go into (...)
Hi, In receiver design, there is well known question, reciprocal mixing. The reciprocal mixing requirement is usually expressed as the interference product produced by reciprocal mixing is below or equal to the floor noise at the ouput when only the MDS(minimum detectable signal) is apply to the input. So the constraint on LO phase noise is PN=
Dear all, I have question about the frequency band conversion problem. I hope anyone explain it to me. In the up-conversion mixer, this is a quadrature input and differential output mixer. Then, the differential signal combines and gives out a single output. My problem is arisen. If a modulated (...)
Something is not ok. Even if you have a high insertion loss input filter (let's say 5dB) and a poor 2dB NF LNA, you get better than 14dB system NF. Download AppCAD software, go to signal-Systems/NoiseCalc and verify what is going wrong.
Dear all, I have question about the quadrature mixer NF simulation setting. I hope anyone could teach me. The attached picture is the NF simulation setup for quadrature mixer. In my design, it has two input ports (Port 1 and Port 2) and generate quadrature signal for the mixer (...)
Hello, a really basic question that confuses some of us. An RF mixer has 3 ports: LOSC RF IF In DOWN-CONVERSION: RF is the input IF is the output What about in UP-CONVERSION? Which port should be the input of the low frequency signal and which one the output of the high frequency (produced) (...)
How to use the analysis (ac small-signal analysis?) in modeling? Should be used balun with a symmetric input / output? Source power to choose a "analogLib -> port"?
mixers are nonlinear blocks and that's why small signal analysis are not valid including AC and s-parametrs.. Instead, a HB analysis by putting current meter can give you the input impedance of a mixer. Or transisent simulation will also give but I prefer to use HB..
You need a mixer that supports near DC on RF input as the one below. The topology will be: Low Pass Filter, mixer, LO (LO=IF-150Hz; IF can be anywhere in the mixer range), IF filter, IF Amplifier, etc.
Hi We all know that the mixer is just a multiplier that can be modeled mathematically as V_out = m(t) * cos(wc*t) where: m(t) is the input modulating signal wc is the carrier frequency if we are upconverting from an IF-frequency then V_out = cos(w_IF*t) * cos(wc*t) = 0.5*(cos((wc+w_IF)t)+cos((wc-w_IF)t))) And we are (...)
If you asked if it works to demodulate broadcast FM, it will work, the same as demodulating FSK. The circuit doesn’t work properly in Narrow-FM systems, as two-way radios, because is designed to demodulate high frequency deviation FM signals. RSSI (Read signal Strength Indicator) indicate the level of the RF signal at the (...)
Being the first time use the mathmatical model of mixer in simulink RF blockset,I made a simple model to check out the conversion of the spectre of the input signal,in my case,the input is composed of two sinus,who have a frequency of 100Mhz and 300 Mhz,the F_sample is set to 2Ghz,the LO frequency of mixer (...)
Dear all, I design a quadrature LO input and IF quadrature combiner down-conversion mixer now. However, I don't know how could I create them? I have tried to use some model in rfLib. It has BB_shifter_spillter and BB_shifter_combiner. However, the 4 output will provide different voltage swing even the phase in quadrature. Could anyone teach me?
Hello everyone, Does there anyone know how to measure the gain mismatch and phase mismatch of this IQ reveiver front end? ......................................|-->gilber cell mixer---> I channel input RF signal--> LNA--> | ......................................|-->gilber cell mixer---> Q channel Thank you for (...)
hi I want to use LT5511 up-mixer to convert my 144MHZ IF to 1.2GHZ RF signal,In datasheet s parameters of ports is given ,is there any handy formula to calculate input impedance at that freq using s parameters and then design 50 match circuit for it?
Hi~all I plan to measure mixer by wafer-probing. mixer is Double Side Band Up-mixer. IF-Differential RF-Differential LO-Differential mixer doesn't have any on-chip balun. Ultimately, I need 3 off-chip balun and two signal gen for IF input and LO input. If (...)
Dear all, I am doing dual up conversion mixer simulation using SpectreRF simulator. However, I do not know the setting of NF and voltage gain simulation. I hope you could give me a step for reference. My simulation input is as follow: RF input: DC with a band from 0 ~ 250MHz (the RF input (...)
if the input rf signals of receiver mixer are not differential, say there is phase error about 20deg(e.g. 0deg and 160 deg respectively), what will happen to mixer performance? due to the function of mixer , the output IF signal will be accurately differential. I am afraid the linearity (...)
Hi all, Currently I am designing down-converter for power line carrier application. One of component in down-converter design is analogue mixer. This analogue mixer would be used to mix (RF) input modulated signal from power line (20KHz - 1MHz) with LO clock signal in order to frequency shift (...)
I noticed something wierd while simulating a switching mixer impedance using PSS and PSP. The impedance seen is dependent on the port's impedance (which it shouldnt be). Any inputs on why this is happening will be helpful!