TW200533192A - Frequency conversion in a receiver - Google Patents

Abstract

A method for frequency conversion of a receiver, including the steps of receiving a signal having a radio frequency and carrying information on a plurality of channels, selecting one of the channels, converting the signal from the radio frequency to a first variable frequency determined by the selected channel, and converting the signal from the first frequency to a desired frequency.

Description

200533192 V. Description of the invention (1) The technical field to which the invention belongs is particularly related to a heavy down-conversion method. The present invention relates to a dual or prior art method of a frequency conversion method for radio frequency signals in a TV tuner / wideband tuner is widely used in a variety of consumer or commercial systems, such as televisions, video recorders or other more complex Electronic equipment, such as cable modems and set-top boxes. There is an annual demand for nearly 300 million broadband tuners worldwide. Broadcasting and cable TV providers have provided more and more types of services' and made their markets develop rapidly. The integration of _playback, video recorder and network functions into a set-top box or a TV set will be the main feature of the future home media center. The Tuner 11 is mainly used as a radio frequency front-end processing circuit for wideband signals. It is used to receive all channels on the channel to select the channel and bitterly select channels and filter out signals from other channels. These tuners operate on The frequency range is 40 to 900_, and has different performance from the traditional TV tuner. I Ge J r Wang this suit. Small size, low power, high guiltyness and simple manufacturing are modern city Shibi cry from you s + One J 卞 & brother tuner's several key issues. In the TV tuner, the frequency shovel is immersed in the old bucket, mb H 丄 八 去 ® ΛΑ The way of leading the way to the tuner design is It is very important. Figure 1 does not show straight in the United States.

# I / μ # i π + # Μ, S disclosed in Patent No. 5, 737, 035 The height of the integrated dual frequency conversion Lei Mangang may not be Union M. The former shirts are not green! x no /, TV chip 5 white early chip circuit. The radio frequency signal is first passed through the antenna 1402 (or subsequent, 4 ^ w ^ " 04 will pass the received frequency band two = _ two through the radio frequency low-pass filter frequency signal and then through one increase or less. After the filter 'injection control low noise Telecom Conductivity Amplifier 1406 to 20 (16

200533192 V. Explanation of invention (2). The first local oscillator 1 450 operates between 1 2 0 and 2100 MHz. Its output signal is mixed with the RF signal in the first mixer 1 408 to generate a first intermediate frequency signal. The carrier frequency is 1 200MHz. Because of the mixture of image and harmonics, this processing method can minimize distortion. The harmonic content of the first intermediate frequency signal is limited by the frequency band of the first mixer 1 4 0 8 and is approximately filtered out.

The first intermediate frequency signal (1 2 0 0 Μ Η z) is mixed with the output signal of a second local oscillator 1 4 1 2 in the second mixer 1 4 1 0 to generate a second intermediate frequency signal. Among them, the second mixer 141 0 is an image rejection mixer (Image-rejection mixer), the output frequency of the second local oscillator 1412 is 1180 MHz, and the carrier frequency of the second intermediate frequency signal is 200. 2. Because the input RF signal is lower in frequency than the oscillating signal. Such signal mixing has the effect of frequency reduction.

However, in the above-mentioned TV tuner, the signals of the out-of-band channels must be eliminated by two external RF surface acoustic wave filters. This will require a linearity and energy-consuming surface acoustic wave driver (SAW

= er) In addition, the phase-locked loop circuit used to generate the first mixed-oscillation signal must operate at a higher frequency, which also makes the output noise of the first mixer very serious. SUMMARY OF THE INVENTION To solve the problems described above, the present invention provides a television tuner, which has the characteristics of low power consumption and high signal-to-noise ratio. A first object of the present invention is to provide a frequency for use in a receiver.

V. Description of Invention (3) 200533192

Method 'includes the following steps: · receiving a radio frequency signal, the signal contains the modulation of the poor channel of the evening; choose one of them-the number is converted from radio frequency to a first frequency', the first frequency is variable and according to = , The selected channel is determined, and then the _ frequency is converted to the _ frequency. It is only a second object of the present invention to provide a receiver, including an antenna that receives a radio frequency signal, the signal including a plurality of channels carrying modulation information; a first local oscillator, generating a signal having a first A first oscillating signal with a frequency; a first mixer that mixes the radio frequency signal with the first oscillating number to generate an intermediate frequency signal; a second local oscillator that produces a second frequency A second oscillating signal; and a second mixer that mixes the far intermediate frequency signal with the second oscillating signal to generate a fundamental frequency signal; wherein the frequency of the intermediate frequency signal is variable and depends on It depends on the selected channel. A third object of the present invention is to provide a receiver, including: an antenna 'receives a radio frequency number, the signal containing a plurality of channels carrying modulation information; a first local oscillator, generating a signal having a first frequency; A first oscillating signal; a first mixer to mix the radio frequency signal with the first oscillating signal to generate a first intermediate frequency signal; a second local oscillator to generate a first oscillating signal having a second frequency Two oscillating signals; a second mixer that mixes the first IF signal with the second oscillating signal to generate a second IF signal; a third local oscillator that produces a third frequency A third oscillating signal; a third mixer that mixes the second intermediate frequency signal with the third oscillating signal to generate a fundamental frequency signal; wherein the first

0828-A40107TWF; VINCENT.ptd Page 7 200533192 V. Description of the Invention (4) The frequency of the IF signal is variable and depends on the selected channel. In the following, an embodiment of a receiver and a frequency conversion method used in the receiver according to the present invention will be described with reference to the drawings. Embodiment Figure 2 shows a television tuner in an embodiment of the present invention. The TV tuner (receiver) includes an antenna 2 1, a low-noise amplifier 2 2, a first local oscillator 2 3, a first mixer 2 4, a second local oscillator 25, and a second A mixer 26 and a surface acoustic wave driver 27. The antenna 21 receives a radio frequency signal, and the radio frequency signal carries information in all television channels. The low-noise amplifier 22 is coupled to the antenna 21 to amplify a radio frequency signal. The first local oscillator 23 generates a first oscillating signal osi having a frequency F01. The first mixer 24 mixes the amplified RF signal with the first oscillating signal 0Si to generate an intermediate frequency signal IS. The second local oscillator 25 generates a second oscillating signal 0S2 with a frequency of F02. The second mixer 26 mixes the intermediate frequency signal IS and the oscillation signal OS2 to generate a fundamental frequency signal BS. The surface acoustic wave driver 27 is connected to the output of the second mixer 26 to drive an external surface acoustic wave filter (not shown). The first local oscillator 23 and the mixer 24 form a first frequency conversion stage 'to convert the radio frequency signal from radio frequency to an intermediate frequency I F, where the value of the intermediate frequency I F is determined according to the selected channel. The value of the intermediate frequency, F, is higher than the frequency of the RF signal (upscaling), and its frequency value is determined so that the amount of noise and false signals from the other channels to the selected channel are minimized. In the middle, the value of the rate IF will vary depending on the selected channel. The second local vibrator 25 and the mixer 26 form a second frequency conversion stage, which converts the signal from the intermediate frequency

200533192 V. Description of the invention (5) The rate is converted to the fundamental frequency (down-frequency). The fundamental frequency pairs 24 and 26 are mirror-rejection mixers: daggers are the same. Noise caused by mixing. The signals outside the band are ^ = image frequency sensing-capacitor tank, not shown in the figure): ^ 24 and 26 The electricity in Figure 3 shows the oscillator 23, which includes a basket of $ 1 ^ 231, phase frequency Detector 232, charge help: rate divider 234, voltage controlled oscillator 235, and second frequency: filter filter 237. The -frequency divider 231 multiplies "table old = 236 and divides frequency by -divisor N. The output terminal of the phase frequency detector 23 522 frequency divider 231. Charge help 丄 Yes-the input terminal is lightly connected to the charge pump: 234 loops and 9% of the output terminal. Voltage Controlled Oscillation ° Eight inputs are creep-coupled to the output of the loop filter 234. The second frequency divider 236 outputs a signal from the voltage-controlled oscillator 235 = -divisor P to output the -th exhaustion signal OS1. Frequency multiplication The -oscillation signal ^ i is multiplied by a -multiplier M, and has a second input terminal of -round out terminal ㈣ to phase frequency detection state 232. The values of N and p are determined by the selected channel. The frequency F1 of the first oscillating signal 0sl is obtained by the following formula: F01 = FR * M / (P * N) FIG. 4 shows a television tuner in another embodiment of the present invention, which uses a triple frequency The conversion includes an antenna 41, a low noise amplifier 42, a first local oscillator 43, a first mixer 44, a second local oscillator 45, a first mixer 46, and a third Local vibrator 47, third mixer

0828-A40107TWF; VINCENT.ptd Page 9 200533192 V. Description of the invention (6) 48 and a surface acoustic wave driver 49. The antenna 41 receives a radio frequency signal, and the radio frequency signal carries information in all television channels. The low-noise amplifier 4 2 is coupled to the antenna 41 to amplify the RF signal. The first local oscillator 43 generates a first oscillation signal OS1 with a frequency of F01. The first mixer 44 mixes the amplified RF signal with the first oscillating signal OS1 to generate a first intermediate frequency signal IS1. The second local oscillator 45 generates a second oscillation signal OS2 with a frequency of F02. The second mixer 46 mixes the first intermediate frequency signal IS1 and the oscillation signal OS2 to generate a second intermediate frequency signal IS2. The third local oscillator 47 generates a third oscillation signal OS3 with a frequency of F03. The third mixer 48 mixes the second intermediate frequency signal IS2 and the oscillation signal OS3 to generate a basic frequency signal BS. The surface acoustic wave driver 49 is coupled to the output terminal of the third mixer 48, and is used to drive an external surface acoustic wave filter (not shown). The first local oscillator 43 and the mixed wave | § 44 form a first frequency conversion stage, which converts a radio frequency signal from radio frequency to a first intermediate frequency I F1, where the value of the intermediate frequency IF1 is determined according to the selected channel . The value of the intermediate frequency I F 1 is higher than the frequency of the RF signal (up-conversion), and its frequency value is determined so as to minimize the amount of noise and false signals coupled from other channels to the selected channel. The value of the intermediate frequency I F 1 will vary depending on the selected channel. The first local oscillator 45 and the mixer 46 form a second frequency conversion stage, which converts the signal from the first intermediate frequency to the second intermediate frequency (down frequency), and its value is the same for all channels. The third local oscillator 47 and the mixer 48 form a third frequency conversion stage, which converts the signal from the second intermediate frequency to the fundamental frequency (down frequency). The mixers 44, 46, and 48 are image rejection mixers, which can eliminate noise caused by the image frequency in the frequency band. Out-of-band signal

200533192_ V. Description of the invention (7) Electric filter in devices 44, 46 and 48. Each oscillator can be the circuit shown in Figure 3. When a-/, is selected, the values of N, P, and M are determined. @ 〃 Frequency Force It must be noted that the triple frequency conversion modulation ratio shown in Figure 4 uses two mixers to complete the wideband to narrowband. Our switching action, while the tuner in Figure 2 uses only one rate reduction becomes the same function. Based on the above, the present invention provides a television debugger with fewer elements. Especially with the US Patent No. 5,73? Low rate and low car, the TV tuner of the present invention has no need to use this ratio. … The surface acoustic wave driver, and thus the work is reduced, although the present invention has been implemented with a preferred method to limit the invention 'anyone skilled in the art: 丄 = within the scope of God, when it can be used without departing from the essence of the invention The scope of protection should be based on the attached towel: ^ and retouching, so the definition of the patent sacrifice of the protection of the present invention shall prevail.

200533192_ Brief Description of the Drawings Figure 1 shows a traditional TV tuner; Figure 2 shows a TV tuner in an embodiment of the invention; Figure 3 shows an oscillator used by a TV tuner in an embodiment of the invention; FIG. 4 shows a television tuner in another embodiment of the present invention. Explanation of symbols 1 40 2, 21, 4 antennas; 1 404 to low-pass filter; 1 406 to conductance amplifier; 1 450, 1412, 23, 25, 43, 45, 47 to local oscillators; 1408, 1410, 24 , 26, 44, 46, 48 ~ mixer; 2 2,4 2 ~ low noise amplifier; 27,49 ~ surface acoustic wave driver; 2 3 1, 2 3 6 ~ frequency divider; 2 3 2 ~ phase frequency Detector; 2 33 ~ charge pump; 234 ~ loop filter; 2 3 5 ~ voltage controlled oscillator; 2 3 7 ~ frequency multiplier.

0828-A40107TWF; VINCENT.ptd Page 12

Claims (1)

200533192 6. Scope of patent application. 1. A method for frequency conversion in a receiver, including the following steps. A channel receives a radio frequency signal. The signal contains multiple choices of one of the channels carrying modulation information. The radio frequency is converted into a first frequency, which is determined according to the selected channel; and, and the first frequency is converted into a second frequency. 2. The conversion method for a receiver as described in item 丨 of the scope of patent application: wherein the first frequency is determined so that the amount of noise and false signals in the selected channel from other channels: combined rate are minimized. Port 3. The conversion method for a receiver as described in item 1 of the patent application range, wherein the first frequency is higher than the radio frequency. 4. As described in item 1 of the scope of the patent application, the method for boat switching in a receiver includes the second frequency to any selected phase gate and conversion method, wherein the second frequency is a fundamental frequency. Receiving " Frequency 6. The conversion method for use in a receiver as described in item 丨 of the scope of patent application, further comprising the following steps: ... reconverting the second frequency to a third frequency. 7. The method for frequency conversion in a receiver as described in item 6 of the scope of patent application, wherein the determination of the first frequency minimizes the amount of noise and false data in the coupling from other channels to the selected channel. 8 · If the patent application range is 6% ^ the frequency used in the receiver 200533192 ------- VI. Patent application range '' ----- Conversion method: Above this radio frequency. 9 · A frequency conversion method for use in a receiver as described in claim 6 of the patent scope ', wherein the second frequency is the same for any selected channel. I 0 · The frequency conversion method for use in a receiver as described in item 6 of the patent application range, wherein the second frequency is lower than the first frequency. II. A frequency conversion method for use in a receiver as described in item 6 of the patent application range, wherein the third frequency is the same for any selected channel. 1 2 The frequency conversion method for use in a receiver as described in item 6 of the scope of the patent application, wherein the third frequency is a fundamental frequency. 1 3 A receiver comprising: an antenna receiving a radio frequency signal, the signal containing a plurality of channels carrying modulation information; a first local oscillator, generating a first oscillation having a first frequency different from the first A signal; a first mixer that mixes the radio frequency signal with the first oscillating signal to generate an intermediate frequency signal; a second local oscillator that generates a second oscillating signal that really has a second frequency; and A second mixer generates a fundamental frequency signal by mixing the intermediate frequency signal with the second oscillating signal; wherein the frequency of the intermediate frequency signal is determined by a frequency change and is determined according to a selected channel. 1 4 · The receiver as described in item 13 of the scope of patent application, wherein the determination of the frequency of the intermediate frequency signal enables coupling from other channels to the selected channel 0828-A40107TWF; VINCENT.ptd Page 14 200533192 -------------. Sixth, the scope of patent application The amount of noise and false signals is the smallest. 1 5 · The receiver as described in claim 3, wherein the first oscillator includes: a first frequency divider that divides a reference frequency FR of a reference signal by a divisor N; phase frequency detection The device has a first input terminal coupled to the output terminal of the first frequency divider; the charge pump has an input terminal coupled to the output terminal of the phase frequency detector; '' ^ a loop filter, An input terminal is coupled to the output terminal of the charge pump; a voltage-controlled oscillator has an input terminal coupled to the output terminal of the return device; um inflammation = the second frequency divider, and one from the voltage control The number of the oscillator is divided by a divisor P to output the first oscillation signal; and the ° frequency multiplier 'multiplies the first exhaustion signal by a multiple M, and has an output terminal coupled to the phase frequency. The second input of the detector. 16 · The receiver according to item 15 of the scope of patent application, wherein N, ρ and M are determined by the selected channel. 17 · The receiver as described in item 3 of the patent application scope, which includes a low noise amplifier lightly connected between the antenna and the first mixer to amplify the radio frequency signal. 1 8 · The receiver according to item 3 of the patent application scope, which includes a surface acoustic wave driver (SAW driver), which is coupled to the second mixer 200533192 " --1 VI. Patent application scope One output end. 19 The receiver as described in item 13 of the scope of patent application, wherein the first and second mixers are image rejection mixers. 2 0 · a receiver, Including: an antenna, receiving a radio frequency signal, the 彳 § 5 tiger bearer carries multiple channels of modulation information; a first local oscillator, generating a first vibrating signal having a first frequency; a first A mixer that mixes the radio frequency signal with the first oscillating signal to generate a first intermediate frequency signal; a second local oscillator that generates a second oscillating signal having a second frequency; a second A mixer that mixes the first intermediate frequency signal with the second oscillating signal to generate a second intermediate frequency signal; a third local oscillator that generates a third vibrational signal having a third frequency; A third mixer that mixes the second intermediate frequency signal with the third oscillating signal to generate a fundamental frequency signal; wherein the frequency of the first intermediate frequency signal is variable and depends on the selected channel; Decide. 2 1 · The receiver as described in item 20 of the patent application range, wherein the first IF signal frequency is determined so as to minimize the amount of noise and spurious signals coupled from other channels to the selected channel. 0828-A40107TWF; VINCENT.ptd Page 16 200533192 6. Scope of patent application First frequency division crying will remove moxibustion.口 * h slave reference frequency FR divisor N; two-phase frequency detector with a first round-by-divide terminal coupled to the first output terminal; ..... human terminal-connected to the phase The frequency detector loop filter has an output end of a frequency divider; a charge pump has an output end, and the input end is connected to the input of the wheel of the charge pump = control vibrator with-input The terminal is connected to the loop frequency divider and outputs a first or second oscillating signal from the voltage-controlled oscillator according to the letter of the wave number and a terminal divisor P; d, is a frequency multiplier, and The first or second oscillating signal is multiplied by a factor of two and has a round-out end coupled to the phase-frequency detector of the second round-in 2 3 · The receiver as described in item 22 of the patent application range, wherein N, P and M are determined by the selected channel. 24. The receiver according to item 20 of the patent application scope, comprising a low noise amplifier coupled between the antenna and the first mixer to amplify the radio frequency signal. 25. The receiver according to item 20 of the patent application scope, comprising a surface acoustic wave driver coupled to an output terminal of the third mixer. 200533192 VI. Scope of patent application 2 6. The receiver according to item 20 of the scope of patent application, wherein the first, second and third mixers are mirror-rejection mixers. 0828-A40107TW; VINCENT.ptd Page 18