Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [cascode]

Anything related to cascode amplifier circuits. A cascode (not to be confounded with *cascade*) circuit is a two-stage direct-coupling amplifier topology using two amplifying elements (usually two BJTs or two FETs).

Anything related to cascode amplifier circuits.

A cascode (not to be confounded with cascade) circuit is a two-stage direct-coupling amplifier topology using two amplifying elements (usually two BJTs or two FETs).

See also Wikipedia on cascode configuration.

88 questions
13
votes
2 answers

When do you want an ESBT (emitter switched bipolar transistor)?

I just found out about ESBTs, which seem to be a hybrid of BJT and MOSFET: When I googled it most links led to STMicroelectronics, so I think currently they're the only manufacturer. I noticed that many devices are high voltage (1000V to more…
stevenvh
  • 145,145
  • 21
  • 455
  • 667
7
votes
2 answers

Difference between cascade and cascode?

What is the difference between cascode amplifier configuration and cascade amplifier configuration?
rrazd
  • 1,667
  • 8
  • 23
  • 30
6
votes
1 answer

Is this cascoded opamp structure unstable by design (LTspice)?

I am playing with a cascode op-amp design and I have problems judging its stability (schematic at the end of the post). When I judge the DC or AC analyses, it all looks good. No peaking and good phase margin well beyond the unity gain point (~10 MHz…
tobalt
  • 18,646
  • 16
  • 73
5
votes
1 answer

How does one set the Q-point for a JFET cascode amplifier, and what are the correct "Idss" requirements for cascoded JFETs?

I am trying to teach myself electronics, and am currently attempting to learn about cascodes with the intent of building an RF amplifier that will amplify a microvolt signal up to line level with minimal noise. My intended approach is a cascode (or…
normal chemist
  • 165
  • 5
4
votes
1 answer

Role of input capacitance for cascode-input op-amp

In the below schematic of a cascode-input op-amp, the input transistors M1 and M2 present no capacitive load to the input signals, because their gate-source and gate-drain voltages are stabilized. The schematic omits frequency compensation…
tobalt
  • 18,646
  • 16
  • 73
4
votes
3 answers

Cascode vs Folded-Cascode

I'm having a hard time understanding what the real benefit of a folded-cascode is over a simple cascode: Also, one more question, is there any significance of there being a low-impedance node (source of M1A) at the drain of M1 (Figure (b))? I can…
AlfroJang80
  • 3,025
  • 2
  • 25
  • 50
4
votes
1 answer

High Voltage Cascode with MOSFET LT Spice Simulation

I'm an electronics engineering student and want to develop a high voltage switch with normal Si N-MOSFETs. After some research, I discovered cascode switches for this application. Most of these cascodes use depletion SiC JFETs. But those are…
Joey Ssymank
  • 41
  • 4
4
votes
1 answer

Biasing high frequency BJT cascode amplifier

So far, no one in the course has gotten both primary spec: 14.125 (with 1 V/V swing either way) nor 3dB-bandwidth of 500kHz to 20MHz using the 2N4427 (datasheet). Vcc = 9V I_CQ = 10mA-15mA I have four questions about the cascode BJT amplifier. 1)…
adamaero
  • 606
  • 1
  • 7
  • 28
4
votes
1 answer

Importance of Source-Body Connection In MOSFET Cascode Amplifier

While reviewing cascode amplifiers, I found an image on Wikipedia of a MOSFET amplifier, which I reproduced here: The image on Wikipedia has the following caption under the image: Since each MOSFET transistor has gate (sic) and source connected,…
cr1901
  • 494
  • 3
  • 12
4
votes
1 answer

MOSFET Cascode: intuitive explanation

How can a MOSFET cascode be explained (not calculated) intuitively? Especiall I would like to know why it's output resistance is high and why the drain voltage of the lower MOSFET M2 is stabilized, i.e. changes very little when the ouput voltage…
Jo123
  • 151
  • 1
  • 3
4
votes
1 answer

Cascoded/Bootstrapped Transimpedance Amplifier

I've come across an interesting transimpedance amplifier toplogy, that reportedly reduces voltage and current noise and compensates for large photodiode capacitance. However, as I'm working with an avalanche photdiode, and I need to bias it with at…
joaocandre
  • 978
  • 2
  • 12
  • 32
3
votes
1 answer

Cascode BJT amplifier DC analysis assumption

simulate this circuit – Schematic created using CircuitLab I am working on the DC analysis of a cascode amplifier. If I assume base current is negligible I get the following equations: From voltage divider: Vb1 = (Rb1/Rb1+Rb2+Rb3) * Vcc, Vb2 =…
Alema416
  • 107
  • 4
3
votes
2 answers

Why cascode transistors contribute little to overall noise in an OTA?

I have read this sentence below in a paper which describes a low noise amplifier. I can't understand the reason why cascode transistors contribute little to overall noise in an OTA?. Can someone explain me the reason? Also, I search in the group and…
vl123
  • 121
  • 1
  • 6
3
votes
2 answers

Why does the "top" transistor in a cascode not set the current?

This has been bothering me for some time. Why is it that the overdrive voltage of the bottom transistor in a cascode controls the DC current, and not the Vgs of the top transistor? Similarly, in an NMOS diff pair with a current mirror on the bottom,…
user45365
  • 61
  • 2
2
votes
2 answers

Folded Cascode op-amp bias point

Below is a minimalistic schematic of a folded cascode op-amp input stage. The node Bias is usually drawn like a fixed voltage, which consequently makes the drain voltage of the input transistors also fixed. simulate this circuit – Schematic created…
tobalt
  • 18,646
  • 16
  • 73
1
2 3 4 5 6