Logarithmic temperature compensation for detectors
AssigneeAnalog Devices, Inc.
InventorVincenzo DiTommaso
Life of this patent
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Abstract
The intercept of a logarithmic amplifier is temperature stabilized by generating a signal having the form H log H where H is a function of temperature such as T/T0. The first H factor is cancelled, thereby generating a correction signal having the form Y log H. The cancellation may be implemented with a transconductance cell having a hyperbolic tangent function. The H log H function may be generated by a pair of junctions biased by one temperature-stable current and one temperature-dependent current. The pair of junctions and the transconductance cell may be coupled together in a translinear loop. A user-accessible terminal may allow adjustment of the correction signal for different operating frequencies.
Claims18
An integrated circuit comprising:
- an RF power detector;
- a compensation circuit coupled to the detector to provide compensation to the detector;
- and
- a user-accessible terminal to allow a user to externally adjust the magnitude of the compensation;
- where the compensation circuit comprises:
- a transistor having a first terminal arranged to generate a bias current of the compensation circuit, and
- an operational amplifier having an input coupled to the user-accessible terminal and an output coupled to drive a second terminal of the transistor in response to an adjustment signal applied to the user-accessible terminal.
An integrated circuit comprising:
- an RF power detector;
- a compensation circuit coupled to the detector to provide compensation to the detector;
- and
- a user-accessible terminal to allow a user to externally adjust the magnitude of the compensation;
- where the compensation circuit comprises:
- a transconductance cell,
- a transistor having a first terminal arranged to generate a bias current for the transconductance cell, a second terminal coupled to receive a reference voltage, and a third terminal coupled to the user-accessible terminal.
An integrated circuit comprising:
- a radio-frequency power detector;
- a compensation circuit coupled to the detector to provide compensation to the detector;
- and
- a user-accessible terminal, where the compensation circuit is constructed and arranged to adjust the magnitude of the compensation in response to a component that is external to the integrated circuit and coupled to the user-accessible terminal.
An integrated circuit comprising:
- a radio-frequency power detector having a temperature dependency;
- a compensation circuit coupled to the detector to provide temperature compensation to the detector;
- and
- two user-accessible terminals;
- where the compensation circuit is arranged to adjust the temperature compensation in response to the values of two external components coupled to the user-accessible terminals.
Dependencies are inferred from the claim text.