Current controlled biasing for current-steering based RF variable gain amplifiers
First Claim
1. a gain system for a wireless transmitter core comprising:
- an automatic gain control circuit for providing differential gain control voltages (V GAIN+, V GAIN−
) corresponding to a level of gain in response to a control signal (VCONT), the automatic gain control circuit controlling the differential gain control voltages to have a linear relationship with the control signal;
a variable gain amplifier for amplifying a data signal IN with the level of gain in response to the differential gain control voltages, an output power of the variable gain amplifier varying between a minimum output power at a minimum gain level of the differential gain control voltages and a maximum output power at a maximum gain level of the differential gain control voltages, the variable gain amplifier receiving a variable current (I VAR) for operating the variable gain amplifier; and
,a current control circuit for adjusting the variable current in response to the differential gain control voltages, the current control circuit minimizing the variable current at the minimum output power and maximizing the variable current at the maximum output power;
wherein the current control circuit includes a combination of a proportional to absolute temperature current source and a complementary to absolute temperature current source to generate the variable current.
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Accused Products
Abstract
An adaptive current control circuit for reduced power consumption and minimized gain shift in a variable gain amplifier. An automatic gain control circuit provides gain control voltages in response to a gain control signal. The gain control voltages are used by the variable gain amplifier to set the gain of the output signal for wireless transmit operations. The adaptive current control circuit receives the same gain control voltages for reducing current to the variable gain amplifier during low gain operation, while providing higher currents during high gain operation. The current that is provided is a hybrid mix of proportional to absolute temperature (PTAT) current and complementary to absolute temperature (CTAT) current for minimizing temperature effects on the gain. The ratio of PTAT current and CTAT current is adjustable for specific temperature ranges to further minimize temperature effects on the gain.
34 Citations
22 Claims
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1. a gain system for a wireless transmitter core comprising:
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an automatic gain control circuit for providing differential gain control voltages (V GAIN+, V GAIN−
) corresponding to a level of gain in response to a control signal (VCONT), the automatic gain control circuit controlling the differential gain control voltages to have a linear relationship with the control signal;a variable gain amplifier for amplifying a data signal IN with the level of gain in response to the differential gain control voltages, an output power of the variable gain amplifier varying between a minimum output power at a minimum gain level of the differential gain control voltages and a maximum output power at a maximum gain level of the differential gain control voltages, the variable gain amplifier receiving a variable current (I VAR) for operating the variable gain amplifier; and
,a current control circuit for adjusting the variable current in response to the differential gain control voltages, the current control circuit minimizing the variable current at the minimum output power and maximizing the variable current at the maximum output power;
wherein the current control circuit includes a combination of a proportional to absolute temperature current source and a complementary to absolute temperature current source to generate the variable current. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A gain system for a wireless transmitter core comprising:
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a variable gain amplifier receiving a variable current for amplifying a data signal with the level of gain in response to differential gain control voltages (V GAIN+, V GAIN−
), an output power of the variable gain amplifier varying between a minimum output power at a minimum gain level of the differential gain control voltages and a maximum output power at a maximum gain level of the differential gain control voltages, the variable gain amplifier receiving a variable current (I VAR) for operating the variable gain amplifier;a temperature sensor for providing an analog signal corresponding to a sensed temperature, a temperature decoder for generating a first ratio control word and a second ratio control word in response to the analog signal received from the temperature sensor; and
,a current control circuit for providing a proportional to absolute temperature current (PTAT) in response to the first ratio control word and a complementary to absolute temperature current (CTAT) in response to the second ratio control word, the current control circuit summing the PTAT current and the CTAT current to provide the variable current. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22)
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Specification