LogSuccDetect (Successive Detection Logarithmic Amplifier
Symbol
Available in ADS
Parameters
Name |
Description |
Units |
Default |
|---|---|---|---|
NumStages |
Number of stages |
None |
5 |
StageGain |
Gain per stage |
dB |
10 |
CurrentSlope |
Gradient of transfer characteristic |
A/decade |
1.e-3 |
Z1 |
Reference impedance for port 1 |
Ohm |
50 |
Notes/Equations
- This amplifier use a successive detection scheme to provide an output current proportional to the logarithm of the input voltage. The amplifier consists of several amplifier/limiter stages (NumStages specifies how many), each having a small signal gain (StageGain specifies the gain). Each stage has an associated full-wave detector, whose output current depends on the absolute value of its input stage. These output currents are summed to provide the output scaled at the CurrentSlope (amp/decade). The output contains amplitude information only, regardless of any phase information. A simplified block diagram of this component is shown in Simplified Block Diagram of a 5-Stage LogSuccDetect.
Simplified Block Diagram of a 5-Stage LogSuccDetect
- Several logarithmic amplifiers are available in ADS: LogACDemod, LogDC, LogSuccDetect, and LogTrue. These components accept an RF input and generate a DC output voltage proportional to the log of the input voltage.