Temperature-compensated PIN-diode attenuator

Circuitry comprising a PIN-diode attenuator, the attenuator comprising:

• an input node, an output node, and first and second bias nodes;
• at least first and second PIN diodes;
• a first resistive network connected between the first PIN diode and the first bias node;
• and
• a second resistive network connected between the second PIN diode and the second bias node, wherein each resistive network comprises a passive, temperature-sensitive device that provides at least partial compensation for temperature-dependent behavior of the attenuator wherein each passive, temperature-sensitive device is an n-type thermistor and at least one of the first and second resistive networks comprises:
• a parallel network comprising a first resistor connected in parallel with the thermistor;
• and
• a second resistor connected in series with the parallel network.

A non-reflective attenuator comprising:

• an input node, an output node, and first and second bias nodes;
• a 90-degree hybrid;
• a first DC-blocking capacitor connected between the input node of the attenuator and an input port of the hybrid;
• a second DC-blocking capacitor connected between an isolated port of the hybrid and the output node of the attenuator;
• a first PIN diode connected at a coupled port of the hybrid;
• a second PIN diode connected at a direct port of the hybrid;
• a first resistive network connected between the coupled port of the hybrid and the first bias node of the attenuator;
• a second resistive network connected between the direct port of the hybrid and the second bias node of the attenuator, wherein each of the first and second resistive networks comprises:
• a parallel network comprising a first resistor connected in parallel with an n-type thermistor that provides at least partial compensation for temperature-dependent behavior of the attenuator;
• a second resistor connected in series with the parallel network;
• and
• a low-pass filter connected to inhibit relatively high-frequency signals in the attenuator from reaching the thermistor, wherein the low-pass filter comprises a capacitor connected in shunt between the first and second resistors.