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APCO P25 Phase 2 - RF ICs

Monday 22 February 2016

Maldon, Essex - CML Microcircuits (CML), is a leading innovator and provider of low-power semiconductors for the global wireless data and two-way radio communications markets. Specialising in RF and baseband IC solutions, CML’s product range provides key benefits to radio manufacturers including: high integration, high performance, low power operation, product longevity and complementary RF plus baseband chipsets.

APCO P25 is the public safety radio standard used across the USA and also deployed in a number of other countries around the world. P25 Phase 2 has a Common Air Interface (CAI) using two-slot Time Division Multiple Access (TDMA), 12.5kHz RF channels and H-CPM / H-DQPSK modulation.

CML’s RF receiver and transmitter solutions have been adopted by major radio manufacturers in their new multi-mode radios.

The recently released CMX994E enhanced performance Direct Conversion Receiver IC provides an optimum solution for a Software Defined Radio (SDR) approach to developing a state-of-the-art P25 radio.  The device provides a flexible solution that can be used as a direct or single conversion receiver from RF directly down to zero-IF, near zero-IF or low IF. By including the complete LNA to I/Q output signal path with variable gain, flexible IF filters, LO frequency dividers and dc offset controls the CMX994E supports compact, highly flexible direct conversion receiver designs. The CMX994E also includes a PowerTrade™ feature that permits performance and power consumption to be traded against one another. This provides enhanced performance when needed and low power consumption at other times, providing an overall highly flexible and configurable solution that can adapt to changing demands.

Integrating the transmitter in the terminal can be managed by one of CML’s I/Q transmitter ICs.  The CMX971 I/Q Modulator IC is commonly used and is ideally suited to address the high performance requirements of APCO P25.

The H-DPSK modulation used by APCO P25 Phase 2 base stations is linear (non-constant envelope) therefore to ensure maximum transmitter efficiency the Power Amplifier (PA) requires linearisation. CML’s CMX998 Cartesian Feed-back Loop (CFBL) transmitter IC provides a proven solution to this complex task.

These devices are just part of CML’s extensive range of integrated RF and baseband/air interface solutions in support of digital radio standards worldwide, such as: TETRA, DMR, dPMR, NXDN, ARIB STDs, PDT along  with legacy analogue FM PMR/LMR systems.

Further details of CML’s high performance RF ICs can be found at

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