Amplifier assembly, receiver comprising said assembly and method for operating a programmable amplifier
View Patent ↗An amplifier assembly and also a receiver including such an amplifier assembly is disclosed, wherein the amplifier includes a programming input for setting the gain thereof. The signal level at the output of the amplifier is compared with a reference level and a counter is incremented in a step-by-step fashion such that the gain in the amplifier is reduced for as long as the output level lies above the reference level. The amplifier assembly enables frequency-dependent received field strength fluctuations that occur in frequency hopping methods to be corrected in a manner dependent on the conditions in the current time slot. The assembly is also suitable for modulation methods that use a modulation with phase and amplitude variation.
1. A receiver, comprising:
a mixer configured to down-convert a radio frequency modulated signal to an intermediate frequency modulated signal;
a programmable gain amplifier configured to receive and amplify the intermediate frequency modulated signal based on a programmable gain value associated therewith;
a demodulator configured to receive and demodulate the amplified intermediate frequency modulated signal; and
a control circuit configured to produce a gain programming control signal for dictating a gain of the programmable gain amplifier based on a level of the amplified intermediate frequency modulated signal at a beginning portion of a time slot, wherein the control circuit is configured to reset the gain of the programmable gain amplifier via the gain programming control signal to a maximum gain setting associated therewith at a beginning of the time slot, and incrementally decrease the gain of the programmable amplifier until the level of the amplified intermediate frequency modulated signal is less than a predetermined threshold value, and wherein the control circuit is further configured to maintain the gain of the programmable amplifier via the gain programming control signal at that level for a remaining portion of the time slot.
2. The receiver of claim 1 , wherein the time slot corresponds to a Bluetooth communication specification, and wherein the beginning of the time slot corresponds to a time period allocated to an access code portion of the time slot, and wherein the gain is subsequently maintained during a time period of the time slot associated with a transfer of useful data.
3. The receiver of claim 1 , wherein the beginning of the time slot corresponds to a time period allocated for transmission of a training sequence or synchronization data.
4. The receiver of claim 1 , wherein the control circuit comprises:
a comparator circuit configured to compare the amplified intermediate frequency modulated signal to a reference value corresponding to the predetermined threshold value, and generate a count control signal in response thereto; and
a counter configured to increment or decrement in a step-by-step fashion the gain programming control signal based on a state of the count control signal.
5. The receiver of claim 4 , wherein the comparator circuit is configured to force the count control signal to a counter enable state when the amplified intermediate frequency modulated signal is greater than the reference value, and force the count control signal to a counter disable or hold state when the amplified intermediate frequency modulated signal is less than the reference value.
6. The receiver of claim 4 , wherein the counter further comprises a clock input, and is configured to increment or decrement the gain programming control signal at a rate associated with a frequency of a clock signal provided at the clock input.
7. The receiver of claim 4 , wherein the counter further comprises a reset input configured to receive a signal indicative of an initiation of a time slot, and wherein the signal is configured to reset the counter, thereby resetting the gain programming control signal to a value indicative of a maximum gain value of the programmable amplifier when the signal at the reset input indicates a beginning of a time slot.