Circuit structure for improving influence on CDMA sensitivity from GSM switch in dual modes handset

Abstract

The invention comprises: a RF amplifier and a receiving filter. It also comprises: a duplexer whose public end is connected to the antenna; two circulators each having public port, transmitting path port and receiving path port, and wherein each public port is respectively connected to the low frequency port and high frequency port of the duplexer; two RF switch groups respectively connected between the two circulators and the receiving path, and wherein each port at each RF switch side is respectively connected to the transmitting path port and the receiving path port of each circulator, and the other port at RF switch side is respectively connected to the output port of RF amplifier and the input end of the filer.

Description

technical field [0001] The invention relates to a circuit structure for improving the influence of a GSM switch on CDMA sensitivity in a GSM / CDMA dual-mode mobile phone. Background technique [0002] The GSM / CDMA dual-mode mobile phone is a mobile communication terminal that supports both GSM and CDMA in standby mode and even simultaneous communication. This type of dual-mode mobile phone has mutual interference when the wireless modules of the two standards work at the same time due to the proximity of frequencies, which has a certain impact on their respective wireless performance, referred to as GC mutual interference. [0003] There are many types of GC mutual interference, and the present invention focuses on a type in which the interference path is relatively subtle and the interference effect is obvious. We found in the research that when GSM is in standby, the switch of the front-end RF switch will have a sudden impact on the sensitivity of CDMA. As long as CDMA is ...

AI Technical Summary

Problems solved by technology

[0007] 2. The impedance transformation of the radio frequency path in the work determined by the GSM circuit structure leads to the spectrum expansion of the CDMA transmission signal in the GSM circuit;

[0008] 3. The spread-spectrum CDMA signal returns through the GSM transmission channel, and radiates into the air through the GSM antenna, and then is received by the CDMA antenna. The power falling in the CDMA receiving frequency band enters the CDMA receiving channel and becomes interference noise, affecting CDMA receiver sensitivity

These circuit structures cause the CDMA signal received from the antenna to fall directly on the RF switch

In the communication process of the GSM circuit, the radio frequency switch switches between the transmission and reception channels, resulting in an instantaneous change in the impedance of the radio frequency channel.

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