The MediaTek MT6635 is a 4-in-1 connectivity chip that contains two 2.4GHz Wi-Fi transceiver front-ends, two 5GHz Wi-Fi transceiver front-ends, a Bluetooth transceiver front-end, a GPS L1-band receiver front-end, a GPS L5-band receiver front-end, and a complete FM receiver in a WLCSP package. The simplified block diagram and how to use MT6635 are shown in Figure 1-1. The control logic at the top controls each subsystem independently. Each subsystem also has a dedicated LDO. A thermal sensor and a low-speed ADC (analog-to-digital converter) are provided to monitor the temperature changes of the MT6635. The MT6635 does not have its own dedicated crystal oscillator. It uses an external (possibly temperature-compensated) oscillator or a clock source from a companion chip in the platform. For 2.4GHz Wi-Fi and Bluetooth, the MT6635 offers an advanced switching mechanism that can quickly switch between Wi-Fi and BT modes. The front end of the transceiver is on the MT6635, while the ADC/DAC (analog-to-digital converter/digital-to-analog converter) is in the matching modem chip. The interface driver/receiver buffer is designed to drive the tracking loading of the PCB. The GPS IP in the MT6635 is similar to Wi-Fi/Bluetooth, so the ADC is in the matching modem chip. In contrast, FM systems integrate the modem and ADC in the MT6635 and do not require an interface driver/buffer.

Compared to its predecessor, MT6631, MT6635 has the following new features:  Wi-Fi 2.4/5 GHz supports MIMO 11AC.  Wi-Fi 5 GHz supports 1*1 VHT80 + VHT80.  1*1 Wi-Fi 5 GHz and Wi-Fi 2.4 GHz dual-band dual-current  Dedicated BT front-end saves BT current and higher TX power  GPS supports L5 band. Support for this advanced feature (GPS L5 band) is defined in the SOC platform datasheet.

Figure 1-1. MT6635 block diagram features  The MT6635 is a 4-in-1 connectivity chip that contains two 2.4GHz Wi-Fi transceiver front-ends, two 5GHz Wi-Fi transceiver front-ends, a Bluetooth transceiver front-end, a GPS L1-band receiver front-end, a GPS L5-band receiver front-end, and a complete FM receiver in a WLCSP package.  Support GPS external LNA 1.2.1 Wi-Fi/bt  2*2 Wi-Fi 5 GHz and Bluetooth WLAN Simultaneous Operation (FDD)  Dual band (2.4 GHz and 5 GHz) two streams 802.11 A/B/G/N/AC RF with 20/40/80 MHz bandwidth  Support for global Wi-Fi 5G channels, including new bands in the US and China (5,925 MHz) and Bluetooth FDD operation  Support 802.11d/e/e/i/j/j/j/k/r/v/w with Companion d-die  Integrated 2.4 GHz/5 GHz PA  Integrated power detector supports per-packet TX power control  Built-in calibration for PVT variation  Configurable Wi-Fi 2.4/5 GHz PA for increased efficiency in low power applications.  Supports external PA and LNA for Wi-Fi 2.4 GHz and Wi-Fi 5 GHz.

Bluetooth  Bluetooth specification v2.1+EDR, 3.0+HS and v4.2+HS compatible  Bluetooth 5 dual mode for LE 2 Mbps, LE long range and advertise extension  Integrated PA  Low power sweep function to reduce power consumption in scan mode 1.2.2 FM  65 to 108 MHz with 50 kHz step  RDS/RBD is supported  Digital stereo modulator/demodulator  Digital audio interface (FM 2-Wire Bus)  Fast seek time 30 ms/channel  Stereo noise cancellation  Audio sensitivity: 3 dbμVEMF (Sinad = 26 dB)  Audio Sinad ≥ 60dB  Counter-judgment  Support for short antennas 1.2.3 GPS  RF supports simultaneous dual-band L1 and L5 operation. (The MT6635 only includes L5 band support in the transceiver component, the SOC platform datasheet further defines support for the entire GNSS L5 function)  RF supports GPS, Galileo, Glonass and Beidou.  Accept GPS + Glonass + Beidou/Galileo at the same time for more accurate positioning  Built-in calibration for PVT variation  Typical RX tracking sensitivity - 163 dBm  Support for external LNAs  Multi-mode filters for different GNSS receiver modes  RF supports GPS, Galileo, Glonass and Beidou.  Accept GPS + Glonass + Beidou/Galileo at the same time for more accurate positioning  Built-in calibration for PVT variation  Typical RX tracking sensitivity - 163 dBm  Support for external LNAs  Multi-mode filters for different GNSS receiver modes