摘要:
A transconductance filter (200) comprises multiple stages of a transconductor (110,120,130) having an input and an output, and a switch (260,265,270) coupled between the output and the voltage source. The switch is operatively responsive to the control signal for coupling and decoupling the voltage source directly to the output of the transconductor at least prior to the time the filter is required to filter the input voltage signal. The voltage source is within a predetermined input voltage range of the transconductor defined by a region in which a transconductance of the transconductor is substantially constant and positive.
摘要:
According to one aspect of the invention, an apparatus is provided which includes a first amplifier and a common mode feedback circuit. The first amplifier includes a first input, a second input, a first output, and a second output. The first input and the second input are coupled to receive a first input voltage and a second input voltage, respectively. The first and second outputs provide a first output voltage and a second output voltage, respectively. The common mode feedback circuit has first and second switched capacitors coupled to provide a common mode feedback signal based on the first and second output voltages to the first and second inputs of first amplifier.
摘要:
A method and apparatus for integrating a plurality of analog input signals. A first integrator(725) having a first pole frequency integrates a first of the input signals and a second integrator(730) having a second pole frequency different than the first pole frequency integrates a second of the input signals. A summer(735) is connected to the first and second integrators to then sum the integrated first and second signals and provide a composite integrated signal prior to transmitting a communications signal.
摘要:
A radiotelephone (104) in a radiotelephone system (100) enters a low power sleep mode and times the duration of the sleep mode using a sleep clock generator (205) having a coarse resolution. The radiotelephone synchronizes timing of the radiotelephone to system timing using an oscillator (116) having a fine resolution. The radiotelephone then exits the low power sleep mode synchronized with system timing.
摘要:
Prior to entry into a low-power sleep mode, a radiotelephone (104) in a radiotelephone system (100) calculates in advance the timing required to wake up selected portions of the radiotelephone and stores the calculated wakeup times in registers (216). Also prior to entry into sleep mode, local timing of the radiotelephone is synchronized to received PN roll boundaries from the radiotelephone system. In the sleep mode, the radiotelephone uses a sleep timer (210) to simulate system timing. When the sleep timer (210) matches the stored wakeup times, the radiotelephone re-activates the selected portions of the radiotelephone, such as an oscillator (116) and a radio frequency portion (109) of an analog front end (108), to exit the sleep mode and reacquire communication with the system. This also permits an early exit from sleep mode, for example to service an interrupt, while maintaining system timing.