Abstract:
A voltage-controlled oscillator (VCO) comprising a first circuit, a second circuit, a comparator circuit, and a control unit. The first circuit can determine an output common mode voltage associated with an output of the VCO. The second circuit can generate an upper control voltage limit and a lower control voltage limit associated with a control voltage received by the VCO based, at least in part, on the output common mode voltage. The comparator circuit can compare the control voltage to the upper and lower control voltage limits. The control unit can determine whether to change a switched capacitance associated with the VCO based, at least in part, on whether the control voltage is outside the upper and lower control voltage limits, thereby maintaining an optimal region of operation for the control voltage.
Abstract:
A gain compensator compensates for the gain variation of a varactor-tuned voltage tuned oscillator (VCO) in a phase lock loop (PLL). The VCO includes a parallel LC circuit having multiple fixed capacitors that can be switched-in or switched-out of the LC circuit according to a capacitor control signal to perform band-select tuning of the VCO. The gain compensator compensates for the variable VCO gain by generating a charge pump reference current that is based on the same capacitor control signal that controls the fixed capacitors in the LC circuit. The gain compensator generates the charge pump reference current by replicating a reference scale current using unit current sources. The number of times the reference scale current is replicated is based on the fixed capacitance that is switched-in to the LC circuit and therefore the frequency band of the PLL. The reference scale current is generated based on a PLL control that specifics certain PLL characteristics such as reference frequency, loop bandwidth, and loop damping. Therefore, the reference pump current can be efficiently optimized for changing PLL operating conditions, in addition to compensating for variable VCO gain.
Abstract:
A controller for an adjustable-frequency oscillator includes a first counter supplied with a stop-count value to count adjustable-frequency oscillator cycles divided by the ratio of desired frequency to reference oscillator frequency, to produce a stop signal when the first counter reaches the stop-count value. A second counter counts cycles of a reference oscillator starting from an initial number related to the stop-count value. The second counter stops counting and produces an end-count when the second counter receives the stop signal from the first counter. A resonant tank circuit includes a bank of capacitors with switches to select resonant tank circuit capacitors. The switches are selectively controlled using the end-count in the second counter. The stop-count value is set for the first counter so that the end count number in the second counter using a ones-complement binary format can be used to iteratively set the switches with minimal digital computation.
Abstract:
A capacitor bank includes a first node, a second node, first blocking capacitors, N first AMOS varactors, second blocking capacitors and N second AMOS varactors. The first blocking capacitors have first terminals connected to the first node and second terminals where a bias voltage is applied. The N first AMOS varactors have first terminals connected to the second terminals of the first block capacitors. The second blocking capacitors have first terminals connected to the second node and second terminals where the bias voltage is applied. The N second AMOS varactors have first terminals connected to the second terminals of the second blocking capacitors and second terminals connected to second terminals of the first AMOS varactors, respectively, wherein N binary coded signals are applied to the respective second terminals of the first AMOS varactors and the second AMOS varactors. Therefore, phase-noise degradation caused by the FM modulation may be avoided.
Abstract:
An integrated receiver with channel selection and image rejection substantially implemented on a single CMOS integrated circuit. A receiver front end provides programable attenuation and a programable gain low noise amplifier. LC filters integrated onto the substrate in conjunction with image reject mixers provide image frequency rejection. Filter tuning and inductor Q compensation over temperature are performed on chip. Active filters utilize multi track spiral inductors with shields to increase circuit Q. The filters incorporate a gain stage that provides improved dynamic range through the use of cross coupled auxiliary differential pair CMOS amplifiers to cancel distortion in a main linearized differential pair amplifier. Frequency planning provides additional image rejection. Local oscillator signal generation methods on chip reduce distortion. A PLL generates needed out of band LO signals. Direct synthesis generates in band LO signals. PLL VCOs are centered automatically. A differential crystal oscillator provides a frequency reference. Differential signal transmission throughout the receiver is used. ESD protection is provided by a pad ring and ESD clamping structure. Shunts utilize a gate boosting at each pin to discharge ESD build up. An IF VGA utilizes distortion cancellation achieved with cross coupled differential pair amplifiers having their Vds dynamically modified in conjunction with current steering of the differential pairs sources.
Abstract:
Exemplary embodiments of the invention provide a reference harmonic oscillator integrated circuit having three or more terminals, with systems and methods for calibrating the harmonic oscillator to a selected first frequency using a limited number of terminals. An exemplary apparatus comprises: a reference harmonic oscillator, a first terminal to receive a supply voltage, a second terminal to receive a ground potential, a third terminal to provide an output signal having an output frequency, and may also include a fourth terminal. One of the first, second, third or fourth terminals is further adapted for input of a calibration of the first frequency. The exemplary apparatus may enter calibration and testing modes in response to various commands such as a calibration mode signal, and may also be configured through one of the terminals for output frequency selection, spread-spectrum output, and output voltage levels.
Abstract:
In wireless application there is made use of a quadrature oscillators that generate signals that are capable of oscillating at quadrature of each other. The quadrature oscillator is comprised of two differential modified Colpitts oscillators. A capacitor bank allows for the selection of a desired frequency from a plurality of discrete possible frequencies. The quadrature oscillator is further coupled with a phase-error detector connected at the point-of-use of the generated ‘I’ and ‘Q’ channels and through the control of current sources provides corrections means to ensure that the phase shift at the point-of-use remains at the desired ninety degrees.
Abstract:
A gain compensator compensates for the gain variation of a varactor-tuned voltage tuned oscillator (VCO) in a phase lock loop (PLL). The VCO includes a parallel LC circuit having multiple fixed capacitors that can be switched-in or switched-out of the LC circuit according to a capacitor control signal to perform band-select tuning of the VCO. The gain compensator compensates for the variable VCO gain by generating a charge pump reference current that is based on the same capacitor control signal that controls the fixed capacitors in the LC circuit. The gain compensator generates the charge pump reference current by replicating a reference scale current using unit current sources. The number of times the reference scale current is replicated is based on the fixed capacitance that is switched-in to the LC circuit and therefore the frequency band of the PLL. The reference scale current is generated based on a PLL control that specifics certain PLL characteristics such as reference frequency, loop bandwidth, and loop damping. Therefore, the reference pump current can be efficiently optimized for-changing PLL operating conditions, in addition to compensating for variable VCO gain.
Abstract:
In one embodiment, the present invention includes a method for determining if a frequency control instruction would cause a first capacitor bank to reach a limit and adjusting the first capacitor bank in a first direction using a calibration value and adjusting a second capacitor bank in a second direction if the first capacitor bank would reach the limit. Furthermore, the calibration value may be calculated and stored in accordance with other embodiments. In such manner, small changes in capacitance and correspondingly small changes in frequency may be effected.
Abstract:
An integrated receiver with channel selection and image rejection is substantially implemented on a single CMOS integrated circuit. A receiver front end provides programable attenuation and a programable gain low noise amplifier. LC filters integrated onto the substrate in conjunction with image reject mixers provide image frequency rejection. Filter tuning and inductor Q compensation over temperature are performed on chip. Active filters utilize multi track spiral inductors with shields to increase circuit Q. Frequency planning provides additional image rejection. Local oscillator signal generation methods on chip reduce distortion. A PLL generates needed out of band LO signals. Direct synthesis generates in band LO signals. PLL VCOs are centered automatically. A differential crystal oscillator provides a frequency reference. Differential signal transmission throughout the receiver is used. ESD protection is provided by a pad ring and ESD clamping structure. Shunts utilize a gate boosting at each pin to discharge ESD build up. An IF VGA utilizes distortion cancellation achieved with cross coupled differential pair amplifiers having their Vds dynamically modified in conjunction with current steering of the differential pairs sources.