CMX998 INN/998/1 CMX980A CMX981 EV9980 PE0001

COMMUNICATION SEMICONDUCTORS CMX998 Cartesian Feed-Back Loop Transmitter IC . . . . . . Transmitter Linearization for High Speed

CML Microcircuits COMMUNICATION SEMICONDUCTORS CMX998 CMX998 Cartesian Feed-Back Loop Transmitter IC . . . . . . Transmitter Linearization for High Speed Data Systems INN/998/1 INN/998/1 www.cmlmicro.com The CMX998 CMX998 · · · · · · · · · · · · · · · Frequency Range: 100MHz to 1GHz Wide-Band Noise: -148dBc/Hz SPI Compatible C-BUS Serial Interface Forward Path Up Converter Reverse Path (Feedback) Down Converter Forward and Reverse Path Gain-Controls Error Amplifiers Selectable Open and Closed Loop Functions 360° Loop Phase-Shift Control Instability Detector Linearization Gains of 30dB or More Achievable Flexible Digital Interface (e.g. to CMX980A CMX980A and CMX981 CMX981) Low Power Requirement (3.0 to 3.6 volts) Available in a Q1 (64 no-leads) VQFN Package EV9980 EV9980 EvKit is Available for IC Evaluation and Demonstration I I and Q Inputs from Tx Modulator Q As a state-of-the-art design for an integrated Cartesian Feed-Back Loop (CFBL), the CMX998 CMX998 improves the efficiency and linearity of transmitters of non-constant envelope modulation by the use of a flexible Cartesian feedback loop. Consisting of an `I' and `Q' up-converter (modulator) in the forward path and `I' and `Q' mixers in the feedback path, the CMX998 CMX998 makes available a complete collection of building-block type circuits on a single integrated circuit that the designer/user can select to perform all of the functions required to produce a clean, linear, Tx output signal in a wide-ranging RF spectrum. Covering a wide RF range, from 100MHz to 1GHz, it is usable with channel bandwidths up to 150kHz. The CMX998 CMX998 offers high performance, low wide-band noise and a large degree of linearization gain. Typically, 30dB of linearization improvement is acheivable. Available in a compact 64 no-leads VQFN package this product is an ideal companion for the CMX981 CMX981 advanced digital radio baseband codec IC in digital radio designs. PA CMX998 CMX998 LO Generator and Phase Control CFBL Functions for: TETRA Terminals TETRA 2 Terminals APCO P25 Phase 2 Aviation Systems Mobile Satellite Terminals Linear Modulation Schemes: QPSK, /4 DQPSK, 8PSK, QAM, OFDM, F4FM Direct Interface to CMX981 CMX981 and CMX980A CMX980A ICs The CMX998 CMX998 The Cartesian loop works to improve the linearity of the Tx Power Amplifier (PA) by the action of a feedback loop. The baseband I and Q format Tx input signal in the forward path and an I and Q demodulated feedback signal in the reverse path, developed from the RF PA output, are each applied to an error amplifier to form a negative feedback, closed-loop system that corrects RF PA distortion. The feedback I and Q demodulator local oscillator phase must be adjusted to align input and feedback I and Q signals. Property Supply Requirement 3.0 to 3.6 Volts Frequency Range 100MHz to 1GHz Wideband Noise Figure -148dbc/Hz Control C-BUS - SPI Compatible Serial Interface Package Style Forward Path Feature Q1 64 No-Leads VQFN The I and Q forward paths of the IC each consist of differential input amplifier stages providing gain/ Evaluation Resource EV9980 EV9980 EvKit attenuation, filtering and level translation via external components and for conversion to a single-ended format. I and Q differential error amplifiers are employed to produce the CFBL error signal by comparing the feedback signal with the reference modulation signal. The `error' signal is a pre-distorted waveform that, when applied to the remainder of the forward path, will produce a perfect signal at the modulation output. The I and Q (up-converter) modulator provides translation from baseband signals to a low noise modulated RF signal. This stage also provides gain control. Input Amplifiers For input signal processing Two of each for I and Q Tx channels Differential inputs Flexible configuration: · DC level translation · Filtering · Signal gain or attenuation Error Amplifiers Compare reference signal with feedback signal Differential inputs Selectable bandwidths via external components to implement loop filters Up Converter I and Q Modulators Low noise output Baseband translation to RF Gain/attenuation settings Feedback (Reverse) Path The feedback path comprises a variable attenuator, an I and Q mixer down-converter and baseband amplifiers and switching operations. Low-noise baseband amplifiers at the mixer outputs provide the correct gain to ensure that signal levels around the loop are optimised for noise and linearity. Various outputs are available at this stage to permit monitoring. The loop switches provide the ability to break the loop and operate in open-loop mode whilst simultaneously reducing the gain of the error amplifiers. Down Converter Low-noise, linear operation Variable attenuation input and output stages Broadband baseband path Minimum time-delay 2 Loop Switching Open/closed loop facilities Facilitates loop phase calibration Instability Detector Detects out-of-band energy Signal peak detector Gain control Functions and Signal Flow `I' Channel Feedback Input Input Amplifiers (A1) Input Amplifiers (A2) A2IP A1IO EAIP A2IO EAIO EAIN MODIP Tx `I' Channel Forward Path _ A1IP + + _ _ A1IN Error Amplifier (`I') + CMX998 CMX998 (Part) EAQP Input Amplifiers (A2) A1QO EAQO EAQN A2QO A2QP MODQN Input Amplifiers (A1) DCMEAS MODIN `Q' Channel Feedback Input I and Q Channel Inputs from Tx Modulator MODQP Tx `Q' Channel Forward Path _ A1QP + _ _ A1QN Tx Outputs to PA + + MON Error Amplifier (`Q) VCC DC Null 4:1 Balun 90 0 /2 Up Converter SCK SDI SDO Level Translation CSN Bus Access and Registers LO Splitter Buffer Divide by 2 Feedback Phase Shift Control FORWARD POWER CMX998 CMX998 (Part) C-BUS Serial Interface PA REVERSE POWER MOP RF Power Detector RESET /2 Band Gap Phase Shift Control Band Gap Circuitry Rx Inputs from RF Sensors Loop Switches Local Oscillator Buffer + Instability Amplifier DIP 1:1 Balun Peak Detector _ DIN Down Converter LOP VREF BVREF LON 1:1 Balun SIQ PDI PDO IAO IAI IASIG SOI SOQ DOQ SII FEEDBACK PATH DOI I and Q Feedback Outputs to Tx Error Amps Local Oscillator Input (a) Please note that with the exception of the band-gap circuitry, power supply inputs, outputs and related components are not shown. (b) Grey arrowheads shown on this diagram represent external, connecting circuitry, details of which are given in the product datasheet. (c) The use of second input amplifiers (A2) is optional. 3 Evaluation, Experimentation and Design-in CMX998 CMX998 Performance The EV9980 EV9980 EvKit is available for the evaluation and experimentation of the CMX998 CMX998 and to reduce design-in time. · · · · · · · · · Tx output spectrum in open loop and CMX998 CMX998 closed loop operation Allows Full Evaluation of the CMX998 CMX998 Operational Frequency Range: 100MHz to 1GHz Complete Demonstration of CFBL Functionality (at 400MHz and 800MHz) Access to RF, Control and Baseband Signals Support and Interfacing for Customer PAs Differential or Single-ended I and Q Inputs 360° Loop Phase-Shift Control Interfaces to CMX981 CMX981 EvKit Can Utilise PE0001 PE0001 EvKit Interface Card for Control from a PC using EV9980 EV9980 Software E V9 980 Open loop (no linearization) gives poor performance Member Companies CML Microcircuits (UK)Ltd COMMUNICATION SEMICONDUCTORS Tel: +44 (0)1621 875500 Fax: +44 (0)1621 875600 sales@cmlmicro.com www.cmlmicro.com CML Microcircuits (USA) Inc. COMMUNICATION SEMICONDUCTORS The CMX998 CMX998, the CMX981 CMX981 and the TETRA System The CMX998 CMX998 fulfils the TETRA requirement. The TETRA standard is a good benchmark for a Cartesian feed-back loop as it calls for good linearity to achieve the required adjacent channel powers of better than -60dBc. The EV9980 EV9980 can be configured, via a dedicated interface, to work alongside the CMX981 CMX981 Advanced Digital Radio Baseband Processor or with a custom baseband system. As an Advanced Digital Radio Processor IC compatible with the TETRA specification, the CMX981 CMX981 includes both I and Q and auxiliary codecs, is compatible with the CMX998 CMX998 and provides a specific DC offset correction register to calibrate-out CMX998 CMX998 DC offsets. Your Local CML Distributor Tel: +1 336 744 5050 and 800 638 5577 Fax: +1 336 744 5054 us.sales@cmlmicro.com www.cmlmicro.com CML Microcircuits (Singapore)PteLtd COMMUNICATION SEMICONDUCTORS Singapore Tel: +65 67450426 Fax: +65 67452917 sg.sales@cmlmicro.com www.cmlmicro.com Shanghai Tel: +86 21 63174107 and +86 21 63178916 Fax: +86 21 63170243 cn.sales@cmlmicro.com.cn www.cmlmicro.com A CML Microsystems Plc Company © 2006 CML Microcircuits Closed loop (CMX998 CMX998 linearization) gives much improved performance Design Resources Design and application support is available from: www.cmlmicro.com/ IC and EvKit Technical Datasheets Application Notes Frequently Asked Questions Application Support via local `Help' desks