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22 Threads found on edaboard.com: Differential Amplifier Active
Hi common mode voltage on differential inputs is dc voltage offset that makes the transistors to get ON and be biased in active region , I think that's the same with your Vbias. rejecting common mode voltage means that the output voltage should not change depending on common mode voltage variations. greater CMRR means that output voltage is less
There's no point of providing matched impedance when driving it with a fully differential amplifier placed near to the ADC. The comment is meant for direct connection to 50 ohm systems, e.g. the balun driver circuit in the datasheet. In the active driver circuit, low common impedance is achieved by the filter capacitors and the driver (...)
Hi everyone ! I would like to know why in the differential mode of the diff amplifier MOS with active current load, the output impedance is looked from the drain and in the common mode of this diff amplifier, the impedance is looked from the source ? I would be very grateful if you can help me ! Regards :)
Hi i'm designing differential pair with active load. Yellow curve is pulse input of differential amplifier. Blue curve is output at drain of M49. As you can see in the blue curve, rising edge is very fast but falling edge is quiet weird. at first voltage falls slowly and then falls exponentially. if that's (...)
Dear Alex Hi Are you referring to a differential amplifier with current source in collectors ?
1. I have read somewhere that while in the holding mode, the input common mode voltage of the differential amplifier is equals to output common mode. Does that necessitates the vcmin range should include vcmout? If not what will happen? During hold mode the amplifier is active. In this state the value of the ou
i need to design a differential amplifier that is immune for 1/f noise. The differential amplifier stage should use active load and no ideal current source is allowable to be used. The maximum power consumption for the amplifier should not exceed 75 ?W. The minimum gain required for the (...)
In a short, the results from post #1 are indicating unsuitable circuit bias. For vx=0, it's apparently almost in saturation. The exact condidtions aren't reported, so we need to guess e.g. about input common mode voltage. It's also unclear, if the differential input is applied single ended or differentially. You can easily achieve clarity about
I had designed a MOS differential amplifier using an active load(Current Mirror) but the gain achieved is very less its around 40 only. I need a gain of 10^4 can anyone tell me how to get that gain? :sad:
For the most basic single ended differential input amplifier with one current source and two active load, both the current source (MOSFET) and active loads (also MOSFET) are required to be biased for expected dc current as I see in text books. Say for example, the current source is to be designed to sink 20uA and the (...)
Hi, Want to design a fully differential opamp used in active rc leap-frog filter composition. Filter amps has 14pF and 15K resistor in the feedback. Gain requirement is 45dB min and GB should be 120MHz. 65nm 1.2V supply. Tried standard 2 stage fully diff topology with miller comp. That consumes approx 1mA per amplifier. Want to reduce the (...)
I have a question regarding the design of a differential amplifier with an active load in cadence. My aim is to make it work with supply voltage 1V and current 10~20uA with STM065nm technology. I have problem swinging and getting the right values for the transistor widths. What should be my approach when designing the (...)
Hi, I am trying to design a gigaherts range cmos differential amplifier using 0.18um process. I have to reach 10GHz. One method I know is using active peaking but I just cant make it work. Please help me. As a starter, I just used a simple differential amplifier with resistive load with the (...)
Hi, While I was reading the basic architecture of differential amplifier, I noticed that the differential pair (say, a nmos pair) usually has a pmos current mirror as its active load. Why pmos current mirror in stead of 2 diode connected pmos transistors? What is the difference? Thanks.
hi, i would like to build a comparator in Output offset storage scheme like depicted As the preamplifier, i want to use the differential amplifier with pmos inputs to avoid body
The circuit you're showing is not a fully differential amplifier, but a differential to single-ended converter; Q3 is not an active load, but a diode. For a fully differential output, you need a diode connected Q5 that sets the base emitter voltages of Q3-Q5. Q5 is driven with some reference current (1/2 I). (...)
What could of amplifier are you using at the CMFB(the one used to bias the active loads) ? Check its input, may be it sinks or sources current that flows through the potential divider resistors causing that voltage difference between the common mode level and Vref . Try using an ideal amplifier or a single ended o/p CMOS (...)
hi, does anyone knows any circuits of a differential passive loop filter? I have to design a fully differential PLL. when designing loop filter, I really dont want to use an active one as I have to design a whole new amplifier. I am thinking of using a differential passive loop filter. Looking forward (...)
buffer stage is to convert the output signal from the VCO core to a rail-to-rail switching signal . This can be achieved by the use of a two-stage active current mirror makes the input stage, which serves both as a differential to single-ended converter and an amplifier. second stage the inverter is designed to make the output signal ful
When a op amplifier is designed, some problems are appeared. For a differential op, 1.the input differential pair determines the input transcondutance ,input common mode range and referred input noise; 2.the common bias current source determines the input transcondutance , slew rate ,input common mode range and CMRR; But (...)