By Amplitude Patents (Class 327/50)
- Reference level crossover detecting (Class 327/78)
- Reference determined by threshold of single circuit element (Class 327/80)
- Plural sources of input signal (Class 327/82)
- Temperature compensation (Class 327/83)
- With bridge circuit (Class 327/84)
- Inverting input or output (Class 327/85)
- With transformer (Class 327/86)
- Having feedback (Class 327/87)
- With source as reference (Class 327/88)
- With differential amplifier (Class 327/89)