摘要:
A television tuner includes an IF output terminal for outputting an IF signal converted from a received television signal to an external source, and a channel-selection PLL circuit for converting a high voltage supplied from an external source to a tuning voltage and for supplying the tuning voltage to an internal tuned circuit. The IF output terminal and a high-voltage input terminal of the channel-selection PLL circuit are connected to each other via a first resistor.
摘要:
An integrated receiver with channel selection and image rejection substantially implemented on a single CMOS integrated circuit is described. A receiver front end provides programable attenuation and a programable gain low noise amplifier. Frequency conversion circuitry advantageously uses LC filters integrated onto the substrate in conjunction with image reject mixers to provide sufficient image frequency rejection. Filter tuning and inductor Q compensation over temperature are performed on chip. The filters utilize multi track spiral inductors. The filters are tuned using local oscillators to tune a substitute filter, and frequency scaling during filter component values to those of the filter being tuned. In conjunction with filtering, frequency planning provides additional image rejection. The advantageous choice of local oscillator signal generation methods on chip is by PLL out of band local oscillation and by direct synthesis for in band local oscillator. The VCOs in the PLLs are centered using a control circuit to center the tuning capacitance range. A differential crystal oscillator is advantageously used as a frequency reference. Differential signal transmission is advantageously used throughout the receiver. ESD protection is provided by a pad ring and ESD clamping structure that maintains signal integrity. Also provided are shunts at each pin to discharge ESD build up. The shunts utilize a gate boosting structure to provide sufficient small signal RF performance, and minimal parasitic loading.
摘要:
A technique to achieve high-speed tuning of a Gm-C circuit, such as, for example, a Gm-C filter. In one embodiment, a master Gm-C time-constant circuit incorporates at least one element (either a transconductance or a capacitance) that is matched to a corresponding element (transconductance or capacitance) in the (slave) Gm-C circuit. A waveform generated by the master Gm-C time-constant circuit is used to control a sampler. In one embodiment, the sampler samples a precision counter so as to result in a sampler output having a polarity that steers the tuning voltage in the necessary direction. A tuning control stage coupled to the sampler output implements an algorithm that causes the tuning voltage to converge, with a predetermined precision, to the desired tuning voltage.
摘要:
An automatic tuning scheme for two active band-pass filters where both filters operate on the signal while simultaneously being tuned using a reference signal. To allow that the amplitude of a reference signal is made small and since both filters demonstrate a good linearity the build-up of the inter-modulation distortion does not occur. The first band-pass filter is tuned with the reference falling into its pass-band. The second band-pass filter is also tuned with the reference placed into its pass-band. The reference is practically eliminated by the virtue of the complexity of the second band-pass filter. Assuming the filter passes the signal for positive frequencies if the reference is made a negative frequency by appropriate 90 degrees phase shifting it will be attenuated by at least 55 dB, which is a sufficient signal-to-reference ratio.
摘要:
A method and apparatus for direct tuning of a component embedded within an integrated circuit includes processing that begins by providing a plurality of frequency dependent control input signals to an input of the integrated circuit. The processing continues for each of the plurality of frequency dependent control input signals by incrementally adjusting the power level of each frequency dependent controlled input signal until the signal strength of an output of the integrated circuit is at a desired signal strength level. The corresponding power level is recorded to produce an adjusted power level for the frequency dependent control input signal. The adjusted power level of each of the plurality of frequency dependent control input signals is plotted to produce a signal strength to frequency relationship. The processing continues by comparing the signal strength to frequency relationship with a desired signal strength to frequency relationship. The process then continues by tuning the component such that the signal strength to frequency relationship more closely resembles the desired signal strength to frequency relationship when the comparison was unfavorable.
摘要:
A multi-band receiver for receiving an input signal having a frequency situated either in a first band or in a second band. The receiver comprising a mixer for combining an amplified signal having substantially the same frequency as the input signal with a periodical signal generated by a local oscillator. The mixer generates an intermediate frequency signal, the intermediate frequency signal (IF) being inputted to an IF band-pass filter. A central frequency of the band-pass filter is substantially equal to a frequency of the intermediate frequency signal. The receiver is characterized in that the central frequency of the IF band-pass filter is substantially independent of a combining mode of the amplified signal and the periodical signal, the combining mode being selected from an upper heterodyning mode and a lower heterodyning mode.
摘要:
A component having an acoustically active material, whose acoustic constants can be at least partially altered. The acoustically active material is located at least partially at a phase transition point and/or in the vicinity of a phase transition point.
摘要:
When the frequency band of an intermediate frequency (IF) signal input to a filter rises due to temperature variation, the center voltage corresponding to the IF signal also rises. As a result, a difference occurs between the center voltage and a preselected reference voltage. An output current produced by converting the difference is so output as to increase a control current, thereby shifting the frequency characteristic of the filter to the higher frequency side. When the frequency band of the IF signal falls due to temperature variation, the center voltage also falls. The resulting difference between the center voltage and the reference voltage is also transformed to an output current. This output current is so output as to reduce the control current with the result that the frequency characteristic of the filter is shifted to the lower frequency side.
摘要:
A method of tuning a trap circuit to a desired frequency is provided. A constant amplitude signal is applied to the trap circuit in a progression of successively different frequency increments. The frequency increments cover a frequency range including the desired frequency. The amplitude of the signal, as modified by the trap circuit is detected and stored at each of the different frequency increments. Successive ones of the stored amplitude values are compared until an amplitude difference is found which is greater than a predetermined minimum difference and is of a polarity indicative of an increase in amplitude with the progression, and is a successor of an amplitude difference which is greater than the predetermined minimum difference and of a polarity indicative of a decrease in amplitude with the progression. The frequency at which the inflection point occurs, as indicated by the two-named amplitude differences, represents the null frequency of the trap circuit. The trap circuit is then tuned to align the null frequency with the desired tuning frequency.
摘要:
A network is provided for attenuating the adjacent channel sound carrier signal in a television receiver. First and second trap circuits are serially coupled intermediate the R.F. mixer and the first I.F. amplifier. One of the trap circuits is tuned to a frequency in the vicinity of and above the nominal frequency of the adjacent channel sound carrier, and the other is tuned to a frequency in the vicinity of and below that of the adjacent channel sound carrier. The two trap circuits are mutually coupled to a degree necessary to produce a composite response curve exhibiting a substantially constant level of maximum attenuation in the vicinity of the nominal frequency location of the adjacent channel sound carrier. The trap circuits provide attenuation in excess of that required to eliminate adjacent channel sound carrier interference over a bandwidth sufficient to encompass expected carrier deviation due to frequency modulation, carrier mislocation, and trap mistuning.