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Analog demodulator for low and medium frequency receiver

A demodulator, analog technology, applied in the field of analog demodulators, can solve problems such as phase error, local oscillation leakage, etc., to achieve the effect of avoiding stability and accuracy, and reducing regional oscillation leakage

Inactive Publication Date: 2004-09-22
MEDIATEK INC
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Problems solved by technology

[0006] Today, due to the advantages of combining with the analog transmission receiver and low energy consumption, the application of analog demodulators in the structure of low-IF or ultra-low-IF receivers has been paid more and more attention. However, the receiver must be The received radio frequency is down-converted to an ultra-low intermediate frequency close to the base frequency, which is likely to cause other problems under the structure of the analog demodulator. In addition to the phase error focused on by the aforementioned known technology, it also includes DC potential offset The local oscillation leakage (LO leakage) caused by (DC Offset) and the high-order harmonic items caused by the local oscillator generator (Local Oscillator Generator) have yet to be resolved

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  • Analog demodulator for low and medium frequency receiver
  • Analog demodulator for low and medium frequency receiver
  • Analog demodulator for low and medium frequency receiver

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[0048] The analog demodulator (Analog Demodulator) disclosed by the present invention is a second-stage analog demodulator placed in a low-IF receiver (Low-IF Receiver), that is, in a low-IF receiver, the The analog demodulator of the present invention is provided with a first-stage demodulator before the radio frequency (Radio Frequency, RF) signal that receives receives the operation of down-frequency for the first time, and then the signal that has gone through once down-frequency Sent to the analog demodulator of the present invention to perform frequency mixing and down-frequency work again.

[0049] Under the structure of applying the analog demodulator to a low-IF receiver, the problem to be overcome is the local oscillation leakage caused by the DC potential offset and the impact of the high-order harmonic term on the system performance. Therefore, the present invention The disclosed analog demodulator can use two DC displacement calibration techniques and one filterin...

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Abstract

An analog demodulator is used in low medium frequency receiver. It has the function taking frequency mixing and mirror image eliminating. The analog demodulator uses at least one calibrating device, DC displacement calibrating circuit and filter device to carry out DC potential shift collimation technology and filter technology for solving the problem, so that the analog demodulator will produce DC potential shift and upper harmonic.

Description

technical field [0001] The present invention provides an analog demodulator (Analog Demodulator) used in a low-IF receiver (Low-IF Receiver), especially refers to a related technology that utilizes DC potential offset calibration and filtering to eliminate Analog demodulator for domain oscillation leakage and higher harmonic terms. Background technique [0002] There are three types of RF Transceiver structures in today's wireless communication systems. The first type is Super-heterodyne, which has the longest history. Because it uses an intermediate frequency component to receive and transmit signals, its working It has the advantage of high sensitivity, but the disadvantage is that it needs more separate components such as IF SAW Filter, which makes the assembly price too high and the space required is too large; the second is direct conversion (Direct Conversio) , or called zero intermediate frequency (Zero IF), its technical feature is that the signal received by the ra...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03D7/18H04B1/16
Inventor 王守琮谷中强叶恩祥
Owner MEDIATEK INC