cascode การใช้

• The CS CG combination is called a cascode amplifier.
• Adding this yields the cascode configuration.
• Because the input impedance of the common-gate amplifier is very low, the cascode amplifier often is used instead.
• Adding the lower FET results in a high input impedance, allowing the cascode stage to be driven by a high impedance source.
• Other CMOS circuit families within integrated circuits include cascode voltage switch logic ( CVSL ) and pass transistor logic ( PTL ) of various sorts.
• For example, a common base may be used as a current buffer at the output of a common emitter stage, forming a cascode.
• A practical solution to this low-input-impedance problem is to place a common emitter stage at the input to form a cascode amplifier.
• The combination of these two form the cascode configuration, which possesses several of the benefits of each configuration, such as high input impedance and isolation.
• Figure 1 shows an example of a cascode amplifier with a common source amplifier as the input stage driven by a signal source, " V " in.
• At 200 MHz, a noise figure of 2.5 ( or 4 dB ) can be reached with the ECC2000 tube in an optimized " cascode "-circuit with an optimized source impedance.
• The first requirement is typically solved with a long-tailed cascode stage ( 2 or 3 double triodes ), the second-with two cathode followers inserted between the driver stage and the power stage.
• The cascode places a common-source amplifier between the voltage driver and the common-gate circuit to permit voltage amplification using a driver with " R S > > 1 / g m ".
• It is commonly used for small-signal devices in radio frequency applications where biasing the drain-side gate at constant potential reduces the gain loss caused by Miller effect, replacing two separate transistors in cascode configuration.
• This topology is rarely used in RF mixer / modulator applications, for a variety of reasons . one being that the linearity advantage of the top linearized cascode is minimal due to the near-square wave drive signals to these bases.
• A new class of microwave pulse generation architecture, the RACE ( Rapid Automatic Cascode Exchange ) pulse generation circuit is implemented using low-cost monolithic IC technology and can produce pulses as short as 1 picosecond, and with repetition rates exceeding 30 billion pulses per second.
• A new class of pulse generator microwave pulse generation microwave pulse generation architecture, the RACE ( Rapid Automatic Cascode Exchange ) pulse generation circuit, is implemented using low-cost monolithic IC technology and can produce pulses as short as 1 picosecond, and with repetition rates exceeding 30 billion pulses per second.
• The cascode circuit can also be built using bipolar transistors, or MOSFETs, or even one FET ( or MOSFET ) and one BJT . In the latter case, the BJT must be the upper transistor; otherwise, the ( lower ) BJT will always saturate unless extraordinary steps are taken to bias it.
• If one were to replace the upper FET with a typical inductive / resistive load and take the output from the input transistor's drain ( that is, a common source ( CS ) configuration ), the CS configuration would offer the same input impedance as the cascode, but the cascode configuration would offer a potentially greater gain and much greater bandwidth.
• If one were to replace the upper FET with a typical inductive / resistive load and take the output from the input transistor's drain ( that is, a common source ( CS ) configuration ), the CS configuration would offer the same input impedance as the cascode, but the cascode configuration would offer a potentially greater gain and much greater bandwidth.
• Ronja however uses a feedbackless design where the PIN has a high working electrical resistance ( 100 kilohms ) which together with the total input capacitance ( roughly 7 pF, 5 pF PIN and 2 pF input MOSFET cascode ) makes the device operate with a passband on a 6 dB / oct slope of low pass formed by PIN working resistance and total input capacitance.