We model and verify analog designs in the presence of noise and process variation using an automated theorem prover, MetiTarski. Due to the statistical nature of noise, we propose to use stochastic differential equations (SDE) to model the designs. We find a closed form solution for the SDEs, then integrate the device variation due to the 0.18¿m fabrication process and verify properties using MetiTarski. We illustrate the proposed approach on an inverting Op-Amp Integrator and a Band-Gap reference bias circuit.

Deep datapath and algorithm complexity have made the verification of floating-point units a very hard task. Most simulation and reachability analysis verification tools fail to verify a circuit with a deep datapath like most industrial floating-point units. Theorem proving, however, offers a better solution to handle such verification. In this paper, we have hierarchically formalized and verified a hardware implementation of the IEEE-754 table-driven floating-point exponential function algorithm using the higher-order logic (HOL) theorem prover. The high ability of abstraction in the HOL verification system allows its use for the verification task over the whole design path of the circuit, starting from gate-level implementation of the circuit up to a high-level mathematical specification.

MetiTarski, an automatic theorem prover for inequalities on real-valued elementary functions, can be used to verify properties of analog circuits. First, a closed form solution to the model of the circuit is obtained. We present two techniques for obtaining the closed form solution. One is based on piecewise linear modeling and the inverse Laplace transform. The other is based on small-signal analysis and transfer function theory. Second, the properties of interest are turned into a set of inequalities involving analytic functions, which are proved automatically using MetiTarski. We verify properties concerning oscillation and the change in gain due to component tolerances.

In this paper we formally specify and verify an implementation of the IEEE802.11a standard physical layer based OFDM (Orthogonal Frequency Division Multiplexing) modem using the HOL (Higher Order Logic) theorem prover. The versatile expressive power of HOL helped model the original design at all abstraction levels starting from a floating-point model to the fixed-point design and then synthesized and implemented in FPGA technology. The paper also investigates the rounding error accumulated during ideal real to floating-point and fixedpoint transitions at the algorithmic level.

This paper proposes a framework for the incorporation of formal methods in the design flow of digital signal processing (DSP) systems in a rigorous way. In the proposed approach, DSP descriptions were modeled and verified at different abstraction levels using higher order logic based on the higher order logic (HOL) theorem prover. This framework enables the formal verification of DSP designs that in the past could only be done partially using conventional simulation techniques. To this end, a shallow embedding of DSP descriptions in HOL at the floating-point (FP), fixed-point (FXP), behavioral, register transfer level (RTL), and netlist gate levels is provided. The paper made use of existing formalization of FP theory in HOL and a parallel one developed for FXP arithmetic. The high ability of abstraction in HOL allows a seamless hierarchical verification encompassing the whole DSP design path, starting from top-level FP and FXP algorithmic descriptions down to RTL, and gate level implementations. The paper illustrates the new verification framework on the fast Fourier transform (FFT) algorithm as a case study.

The Signal Processing WorkSystem (SPW) of Cadence is an integrated framework for developing DSP and communications products. Formal verification is a complementary technique to simulation based on mathematical logic. The HOL system is an environment for interactive theorem proving in a higher-order logic. It has an open user-extensible architecture which makes it suitable for providing proof support for embedded languages. In this paper, we propose an approach to model SPW descriptions at different abstraction levels in HOL based on the shallow embedding technique. This will enable the formal verification of SPW designs which in the past could only be verified partially using conventional simulation techniques. We illustrate this novel application through a simple case study of a Notch filter.