70 results about "Gilbert cell" patented technology

A low noise multi-loop radio frequency synthesizer is disclosed for the read channel in a hard disk drive, and for RF wireless communications local oscillator applications. The frequency synthesizer receives an input reference signal having a frequency fR, into a fine tune phase locked loop and into a coarse tune phase locked loop. Driven by the input reference signal, the fine tune PLL outputs a fine tune signal with a frequency fR.P, where P is an integer, while the coarse tune PLL, also driven by the same input reference signal, outputs a coarse tune signal with a frequency fR.A, where A is an integer. A translation phase locked loop has a unity multiplication factor and is driven by the fine tune signal output. The frequency synthesizer finally has a Gilbert cell double balanced mixer coupled between the coarse tune and the translation phase locked loops, wherein the Gilbert cell mixer combines the coarse tune signal and the output signal of the translation phase locked loop and couples the mixed signal into the translation phase locked loop. The translation loop outputs a signal with a frequency which is proportional to the linear sum of the coarse tune signal and the fine tune signal.

In a communication semiconductor integrated circuit, a capacitance included in a filter on the output side of a mixer circuit is reduced without requiring the cutoff frequency of the filter to be changed. A Gilbert cell circuit is used as a mixer circuit which combines, for downconversion, a reception signal and a local oscillator signal. A low-pass filter for removing unwanted waves from output is composed of load resistors of upper stage differential transistors and a capacitive element provided between differential output terminals. The resistances of the load resistors are increased, and a current circuit for applying a current to emitters or collectors of the upper stage differential transistors is provided, so that a current to make up for a decrease in current amount attributable to the increase in load resistance can be applied from the current circuit to lower stage differential transistors.

A modulator apparatus operating at a low supply voltage, configured for receiving an input-voltage signal in base band and supplying an output-voltage signal at a given modulation frequency under control of a signal generated by a local oscillator and comprising a transconductor stage that carries out a voltage-to-current conversion of said input-voltage signal. A voltage-to-current conversion module is coupled to a current-mirror module configured for mirroring a current in a Gilbert-cell stage, which supplies an output-voltage signal under the control of said signal generated by the local oscillator. The Gilbert-cell stage further comprises an output load for carrying out a current-to-voltage conversion and supplying the output-voltage signal. Said transconductor stage further comprises a differential feedback network configured for reproducing said input-voltage signal on a differential load included in said voltage-to-current conversion module.

A signal processing system and method. The inventive system includes a first circuit for distributing an input signal between two or more channels in a current mode of operation. A second circuit is disposed in each of the channels for processing the input signal and providing an output signal in response thereto. A third circuit is provided to combine the signals output by the processing circuit. A fourth circuit is included for controlling the first and the third circuits. In a specific illustrative embodiment, the system further includes a radio frequency stage for downconverting a received signal and providing the input signal in response thereto. In the specific embodiment, the first circuit includes a mixing circuit. The mixing circuit includes Gilbert cells and circuitry for providing automatic gain control for each of the channels individually. The Gilbert cells and the automatic gain control circuitry are driven by a transconductance amplifier and therefore operate in a current mode. Differential digital automatic gain control signals are provided in response to a channel select signal from a digital control circuit. The inventive circuit provides multiple IF channels which may be filtered individually. The invention thereby provides wide band operation in a simple, single stage implementation that consumes little power. Further, the current mode thereof is effective in the reduction of insertion loss.

A mixer with integrated filter for single-ended image rejection is provided, including a single-end to differential (S-to-D) converter, an image rejection notch filer and four Gilbert cell switches. The mixer uses the S-to-D converter as the input cell of the mixer to replace a conventional differential pair circuit. With the converter, the mixer is directly connected to the single-ended LNA, and the output voltage swing of the LNA will be transferred into a differential signal. The image rejection filter is placed between the S-to-D converter and the Gilbert cell switches to filter the image signal from the converter. Thus, only the desired RF signal passing through the Gilbert cell switches will be converted to IF. The notch filter in the mixer of the present invention includes a third-order LC filter and a Q-enhanced circuit. The third-order LC filter has a switch capacitor array to tune both the desired frequency and the image frequency simultaneously. The Q-enhanced circuit includes a programmable current control to adjust the bandwidth and the image rejection of the notch filter.

A Gilbert cell mixer for a wireless transceiver includes a first stage that performs voltage to current conversions and that includes first and second transistors that are operated in a saturation region and third and fourth transistors that are operated in a triode region. A second stage communicates with the first stage and that performs frequency conversion. A biasing circuit communicates with the first stage to maintain a substantially constant input linear range over temperature and process variations.

The invention, which belongs to the radio frequency integrated circuit design technology field, more particularly relates to a Gilbert cell mixer with automatic optimal bias and harmonic wave control. The mixer comprises a basic Gilbert frequency mixing unit, an optimal bias circuit and a harmonic wave control circuit. The Gilbert frequency mixing unit consists of a transconductance level, a switch level, and a load level. The optimal bias circuit includes duplication or reduction with a same proportion of a transconductance-level device of the Gilbert frequency mixing unit, a resistor chain, and operational amplifiers, wherein weak currents flow through the resistor chain and the operational amplifiers form two feedback loops. A middle point of the resistor chain in the optimal bias circuit provides a direct current bias for a transconductance tube in the Gilbert frequency mixing unit. And the harmonic wave control circuit is composed of an adjustable active inductance and a harmonic wave control capacitor; and the harmonic wave control circuit is connected to a drain terminal of the transconductance tube of the Gilbert frequency mixing unit. According to the invention, accuracy of a generated optimal bias is optimized; and a secondary harmonic wave feedback effect is overcome. Besides, the Gilbert cell mixer with automatic optimal bias and harmonic wave control is suitable for application to a wireless communication transceiver circuit needing an active mixer with high linearity.

The thermal interference due to the self heating of transistors constituting a gilbert cell circuit is reduced, thereby largely improving the receiving sensitivity to signals. A mixer circuit composed of a gilbert cell circuit comprises transistors T1 to T6. Each of the transistors T1 to T4 is con figured so that four transistors may be connected in parallel. In a layout on a semiconductor chip, four transistors T1a to T1d and T2a to T2d respectively constituting the transistors T1 and T2 are respectively separated into two pairs, and the respective two pairs are laid out in a crisscross shape so that they are crossed with each other. Similarly, four transistors T3a to T3d and T4a to T4d respectively constituting the transistors T3 and T4 are respectively separated into two pairs, and the respective two pairs are laid out in a crisscross shape so that they are crossed with each other. Thus, the thermal influence applied on the transistors T1 to T4 is uniformed.

Multiple input and/or gain stage Gilbert cell mixer designs are disclosed. The designs allow one input to be turned on at a time, and are suitable, for example, for use in receiver and transmitter applications. In addition, the designs allow for the inputs of the multi-input Gilbert cell mixer to be connected together, thereby allowing for switching of gain states within the Gilbert cell mixer. The mixer design may include, for example, a Gilbert cell mixer stage, and a plurality of input/gain stages. Each input/gain stage has its output connected to the input of the mixer stage, and is configured for receiving an input signal and applying a gain factor to that input signal to provide a signal for mixing with the LO. Each input/gain stage is configured with stage select circuitry for enabling or disabling that stage, so that only one input/gain stage is active at a time.

The invention discloses a seven-bit high-precision broadband active phase shifter for a radio frequency/millimeter wave frequency band, which is characterized in that a single-ended signal output by apreceding-stage circuit is converted into a differential signal through a single-ended to differential passive balun, and four paths of I/Q orthogonal signals are generated through a second-order multiphase filter of an RC orthogonal network; providing gain for the generated four paths of I/Q orthogonal signals through the corresponding Gilbert units and realizing vector synthesis of the orthogonal signals; the synthesized signal is converted into a single-ended signal through the active balun, and the single-ended signal is amplified and output through the phase fine adjustment VGA; a vectorsynthesis quadrant is selected through a quadrant selection switch by adopting high two bits of a seven-bit digital control code, vector synthesis is realized by controlling the current magnitudes oftwo Gilbert units through a numerical control current array in the middle four bits, and phase fine adjustment is realized by controlling a switched capacitor in a VGA at the lowest bit. The invention has the advantages of simple circuit, low power consumption and small area, and can meet the beam scanning requirement of the phased array system.

The invention discloses a low power consumption and high linearity gain controllable active orthogonal frequency mixer. The frequency mixer is mainly used in a radio frequency front-end circuit, carries out up-conversion on an intermediate frequency signal, and converts a useful signal to a radio frequency domain, so that an antenna radiates the useful signal to a transmission medium. A large signal is processed in a radio frequency transmitter channel, and large distortion of the signal should be avoided, so that a module in a transmission channel should have high linearity. According to the invention, a differential operational amplifier and feedback technology is used to improve the linearity of a transconductance line of the traditional Gilbert unit; a switch resistor array is added to realize the configuration of frequency mixer gain; an orthogonal conversion structure can effectively inhibit the generation of an image signal; and the pressure of filtering of the radio frequency domain is reduced.

The invention relates to a vector modulation phase shifter for reconfigurable antenna array beamforming, comprising: an input balun for converting a single-ended input signal into a differential inputsignal; an orthogonal signal generator, wherein the differential input signal passes through the orthogonal signal generator to generate two paths of orthogonal differential signals, namely an I-pathsignal and a Q-path signal; a variable gain amplifier comprising an I-path variable gain amplifier used for carrying out amplitude modulation and vector synthesis on the I-path signal, and a Q-path variable gain amplifier used for carrying out amplitude modulation and vector synthesis on the Q-path signal; and an output balun used for converting the differential signal into a single-ended signaland outputting the single-ended signal. The variable gain amplifier is suitable for the SiGe BiCMOS process, the balun of a transformer structure is adopted, phase and amplitude imbalance is reduced,the bandwidth of orthogonal signals is widened through the low-coupling-coefficient quadrature coupler, and the amplitude control precision is improved through the variable gain amplifier achieved bycontrolling bias currents combined with the Gilbert cell.

A dynamic current steering mixer. The dynamic current steering mixer comprises a Gilbert cell mixer core, a pair of load devices, a dynamic current steering cell, and a transconductor cell. The Gilbert cell mixer core has first and second nodes, receives a first differential input signal, and provides a differential output signal at the first nodes thereof. The load devices are respectively coupled between the first nodes of the Gilbert cell mixer core and a first fixed voltage. The dynamic current steering cell has third nodes coupled to the second nodes and fourth nodes. The transconductor cell is coupled between the fourth nodes and a second fixed voltage and receives a second differential input signal. The dynamic current steering cell alternately steers current of the transconductor cell to or away from the Gilbert cell mixer core.

A stacked Gilbert cell mixer performs two frequency conversions in at least one of a wireless transmitter and receiver and includes a first stage of the stacked Gilbert cell mixer that converts a voltage signal input to the stacked Gilbert cell mixer to a current signal. A second stage of the stacked Gilbert cell mixer communicates with said first stage of the stacked Gilbert cell mixer and performs a first frequency conversion. A third stage of the stacked Gilbert cell mixer communicates with the second stage of the stacked Gilbert cell mixer and performs a second frequency conversion. Said first stage includes first and second transistors, said second stage includes third, fourth, fifth and sixth transistors and said third stage includes seventh, eighth, ninth and tenth transistors.

The present invention provides a semiconductor integrated circuit for communication (RF IC) realizing high yield without deteriorating a carrier leak characteristic even when a modulation circuit is formed by using cheep parts with large variations. In a semiconductor integrated circuit (RF IC) including: an input circuit constructed by a differential amplifier circuit and a level shifter, which is provided on the ante stage of a mixer of a differential circuit called a Gilbert Cell; and a modulation circuit that performs modulation by adding an I/Q signal and a carrier wave signal, a calibration circuit for canceling a DC offset in an output of the input circuit is provided.

An integrated circuit may include a receiver and/or a transmitter that performs third order sub-harmonic conversion. The integrated circuit may include a Gilbert cell active mixer with three or more serially-connected transistors in each of the mixer's four branches. Alternatively, the integrated circuit may include a quad-ring passive resistive mixer with three or more serially-connected transistors in each of the mixer's four branches. Alternatively, the integrated circuit may include a logic circuit and a mixer. The logic circuit may apply logic operations to periodic logic signals having a local frequency and to delayed versions thereof to produce reference signals having a dominant spectral component at three times the local frequency. The mixer may mix input signals with the reference signals to produce output signals having a dominant spectral component at three times the local frequency less a center frequency of the input signals.

The invention discloses a mixer, which belongs to the technical field of mixers. The mixer comprises a transconductance stage, a switching stage and a load stage, wherein transconductance stage adopts a DMGTR (Differential Multiple Gate Transistor) structure consisting of a fully differential pair transconductance and a pseudo-differential pair transconductance; and the switching stage consists of two foldable Gilbert units, one Gilbert unit serves as an in-phase channel of signals, the other one serves as a quadrature channel of signals, the two Gilbert units are both connected with the output terminal of the transconductance stage, and the output terminal of each Gilbert unit is connected with the load stage consisting of two resistors. According to the invention, the linearity of the mixer is greatly improved, and higher gains can be obtained at the same time.