Texas Instruments Corporation

Srinivasan Venkatraman

Abhijit Das

Gregory Eric Howard

Naveen Krishna Yanduru

Danielle Griffith

Shanthi Bhagavatheeswaran

Hugh Thomas Mair

Gireesh Rajendran

Anil Kv Kumar

Debapriya Sahu

Saravana Kumar Ganeshan

Sudhind Dhamankar

A system and method integrates signal filters in a multiband transceiver. A preferred embodiment comprises an amplifier with a first tunable capacitor coupled to a signal input and a tunable filter. The tunable filter comprises an input stage with a first pair of inductors arranged in a dipole configuration and a second tunable capacitor coupled in parallel to the first pair of inductors and an output stage inductively coupled to the input stage, the output stage includes a second pair of inductors also arranged in a dipole configuration and a third tunable capacitor coupled in parallel to the second pair of inductors. The inductors are realized using bond wire or any other high Q material. The first tunable capacitor, the second tunable capacitor, and the third tunable capacitor can be tuned using a master-slave tuning configuration to adjust the operating frequency of the amplifier and the tunable filter to enable frequency band compatibility with multiple communications protocols.

Integrated radio frequency filters for multiband transceivers

Methods and apparatus to integrate image rejection into quadrature mixers are disclosed. A disclosed image-rejection quadrature mixer comprises a quadrature mixer, and a cross-coupled differential pair of transistors to provide a complex filter response, wherein the mixer and the transistors are integrated on a common silicon substrate.

Methods and apparatus to integrate image rejection into quadrature mixers

Methods and apparatus to bias a backgate of a power switch while preventing latchup are disclosed. A disclosed method of biasing a backgate of a power switch comprises: if a voltage of a first power supply rises before a voltage of a second power supply, initially biasing the backgate with a voltage based on the first power supply; and if the voltage of the first power supply rises after the voltage of the second power supply, biasing the backgate with a voltage based on the second power supply.

Methods and apparatus to bias the backgate of a power switch

System and method for correcting an inaccurate clock with the use of an accurate reference clock. A preferred embodiment comprises repeatedly counting clock cycles in a clock signal generated by the inaccurate clock for a specified period of time, after the completion of each specified period of time, computing a delta value based on the clock cycle counts of the clock signal of the inaccurate clock, accumulating a delta sum value, and computing a clock adjustment value for the inaccurate clock based upon the delta sum value. The reference clock is used to mark the end of each specified period of time.

System and method for correcting an inaccurate clock

A digital tuning circuit which generates a digital code representative of a difference of signals generated by a mirror trans-conductor circuit (having electrical characteristics similar to a trans-conductor circuit in a filter) and a reference circuit. The digital code is used to adjust the trans-conductance of both the mirror trans-conductor circuit and the filter. Some of the most/more significant bits may be used to selectively activate the respective trans-conductor elements contained in the mirror trans-conductor circuit and the filter. The remaining bits may be used to fine-tune the trans-conductance of the trans-conductor elements and the filter.

Adjusting the trans-conductance of a filter

EMI caused on a sensitive pin by large electric current flowing through a load pin when driving a high load is reduced or substantially eliminated. An equal amount of current, but in opposite direction, is caused to be flown in another pin ('third pin') located close to the load pin. As a result, the EMI caused by the third pin cancels the EMI generated by the load pin. During a discharge phase, a fourth pin carries and equal amount of current, but in opposite direction, to that in the load pin. The third and fourth pins may be formed by power supply pin and ground pin. A control path may avoid a path from the third pin to the fourth pin during both the charging and discharging phases. In addition, the high load may be driven by a programmable driver which uses an amount of current proportionate to the extent of load, thereby avoiding parasitic currents. EMI is further reduced as a result.

Reducing electro magnetic interference (EMI) in integrated circuits operating on both analog and digital signals

A transconductor circuit, including a differential transconductor amplifier circuit. The transconductor circuit includes an input pair of transistors adapted to receive a differential input voltage, as well as a pair of output terminals adapted to provide a differential output current. A second pair of transistors provides current to the input pair of transistors. A floating voltage circuit is adapted to generate a floating voltage corresponding to a common-mode voltage of the differential output nodes and to control the second pair of transistors in response to the floating voltage to stabilize the common-mode voltage of the differential transconductor amplifier circuit.

Biasing circuit for transconductors

A filter circuit uses a trans-conductor circuit coupled to a control circuit having similar characteristics as the trans-conductor circuit. The control circuit is used to set and/or control the quiescent voltage of the trans-conductor circuit. As a result, the trans-conductor circuit may be designed to operate across a large frequency range while consuming minimal power. The control circuit may be operated using direct current (dc) voltage and may be implemented similar to the trans-conductor circuit implemented in the filter circuit.

Filter circuits based on trans-conductor circuits

The current passing in a main trans-conductor circuit is compared in analog domain with a reference current. If the passing current exceeds the reference current, another trans-conductor circuit may be switched on to cause the effective area of trans-conductor circuits to be increased. Using such a feature, the trans-conductance value may be maintained substantially constant without substantially increasing power.

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Dallas, TX, United States of America

Srinivasan Venkatraman