Abstract:
A method and apparatus is provided for detecting the output power of a power amplifier. The output power is detected by detecting the absolute values of the voltage and current at the output of the amplifier and mixing the detected voltage and current to generate a signal related to the output power.
Abstract:
A method includes controlling a mixer gain to provide a range of selected power output levels from the mixer using a first control scheme for a low portion of the range and using a second control scheme for a high portion of the range. Using the selected mixer gain, incoming baseband signals may be upconverted in the mixer to a transmission frequency and output from the mixer at the selected power output level.
Abstract:
An RF transmitter (104) includes a shared local oscillator circuit (126), transmit path circuitry (120, 122, 124), a divider (134), and a lowpass filter (322). The shared local oscillator circuit (126) generates a shared LO signal (116). The transmit path circuitry (120, 122, 124) mixes a baseband signal (107) and an IF mixing signal (116) to provide an IF signal (112), and converts the IF signal (112) to an RF transmit signal (105) at a desired frequency using an RF mixing signal received at a mixing input thereof. The divider (134) divides the shared LO signal (116) to provide an unfiltered RF mixing signal. The lowpass filter (322) has an input for receiving the unfiltered RF mixing signal, and an output coupled to the mixing input of the transmit path circuitry (120, 122, 124) for providing the RF mixing signal.
Abstract:
Mixing circuitry for quadrature processing in communication systems and related methods are disclosed. The weighted mixing circuitry allows for arbitrary dividers to be utilized in generating the mixing signals for quadrature processing and thereby provides a significant advantage over prior architectures where 90 degree offset I and Q mixing signals were needed for quadrature mixing.
Abstract:
An isolation system is provided that is suitable for use in telephony, medical instrumentation, industrial process control and other applications. Preferred embodiments of the invention comprise a capacitive isolation barrier across which a digital signal is communicated. The system provides a means of communication across the isolation barrier that is highly immune to amplitude and phase noise interference. Clock recovery circuitry may be employed on one side of the isolation barrier to extract timing information from the digital signal communicated across the barrier, and to filter the effects of phase noise introduced at the barrier. Delta-sigma converters may be disposed on both sides of the isolation barrier to convert signals between analog and digital domains. An isolated power supply may also be provided on the isolated side of the barrier, whereby direct current is generated in response to the digital data received across the isolation barrier. A bidirectional isolation system is provided whereby bidirectional communication of digital signals is accomplished using a single pair of isolation capacitors. In preferred embodiments, the digital data communicated across the barrier consists of digital delta-sigma data signals multiplexed in time with other digital control, signaling and framing information. Finally, the isolation system may include a pulse transformer to accommodate ADSL circuitry, whereby power is transmitted through the pulse transformer.
Abstract:
A circuit for determining a value of a variable capacitor includes first circuitry for generating a first indication when a variable voltage across the variable capacitor exceeds a threshold voltage. Second circuitry generates a second indication when a reference voltage across a reference capacitor exceeds the threshold voltage. Control logic responsive to the first and second indications generate a control signal indicating whether the first indication or the second indication occurs first. A successive approximation engine generates an N-bit control value responsive to the control signal. A variable current source is responsive to the N-bit control value for generating a variable current to the first circuitry. A reference current source generates a reference current to the second circuitry.
Abstract:
An integrated control circuit is disclosed including a central processing unit operating in a normal full system power mode and in a reduced system low power mode, and a memory. A plurality of peripheral units are provided, at least one of which includes an input/output for interfacing with at least an external system for receiving information therefrom and a process block. The process block processes the received information from the external system and during the processing of the received information, data is stored in the at least one peripheral unit, and data is transferred at least to or at least from the memory. The input/output and process blocks are fully operable in the full system power mode and the reduced system power mode. A direct memory access (DMA) transfers data directly between the at least one peripheral and the memory when such data transfer is required by the peripheral. The DMA operates in a full power DMA mode when data transfer is required and a low power DMA mode when data transfer is not required. The central processing unit is operable, in the normal full system power mode, to interface with the memory and with the at least one peripheral unit to access data stored by the at least one peripheral unit.
Abstract:
A method and apparatus for synthesizing high-frequency signals, such as wireless communication signals, includes a phase-locked loop (PLL) frequency synthesizer with a variable capacitance voltage controlled oscillator (VCO) that has a discretely variable capacitance in conjunction with a continuously variable capacitance. The discretely variable capacitance may provide coarse tuning adjustment of the variable capacitance to compensate for capacitor and inductor tolerances and to adjust the output frequency to be near the desired frequency output. The continuously variable capacitance may provide a fine tuning adjustment of the variable capacitance to focus the output frequency to match precisely the desired frequency output. During fine tuning adjustment, the PLL may be controlled by a plurality of analog control signals. The analog control signals may be derived by first generating a plurality of phase shifted signals from a divided version of the VCO output clock. Second, the phase differences between the plurality of phase shifted signals and a divided version of a reference clock may be detected and then converted to the analog control signals.
Abstract:
A semiconductor package includes a package substrate and an integrated circuit. The package substrate has a first surface. The integrated circuit couples electrically to the first surface of the package substrate. The integrated circuit and the package substrate together form the semiconductor package. The semiconductor package also includes a first inductance circuit and a second inductance circuit, both formed within the semiconductor package. The first and second inductance circuits couple to each other in parallel. The first and second inductance circuits have substantially symmetrical geometric characteristics.
Abstract:
An exemplary PLL circuit includes a VCO responsive to a plurality of sub-varactor control signals. A digital loop filter for the PLL digitally generates a varactor control word, which is digitally expanded into a plurality of digital values, each of which is conveyed to a corresponding one of a plurality of DACs. A multiplexer is configured to respectively convey the DAC output signals to a group of sub-varactor control signals according to the varactor control word, and to drive remaining sub-varactor control signals to either the full-scale high value or the full-scale low value of the DAC outputs. Each of the DACs preferably includes a hybrid first order/second order sigma-delta modulator, and in certain embodiments, a NRZ-to-RZ coder circuit, and a linear filter circuit.